In today’s closely balanced and highly polarized political environment, the line between victory and defeat for the two parties has grown so thin that control of the White House and Congress typically pivots on the small number of contests within reach for both sides. That means a tiny handful of races this year will likely serve as the tipping points that set the direction for a nation of nearly 335 million people.
Close elections that leave power in Washington teetering between the two parties have become a defining feature of modern American politics. Neither party has maintained simultaneous control of the White House and both congressional chambers for more than four consecutive years since 1968 – after one party or the other enjoyed such unified control almost constantly for the seven decades before that. The Senate and House are now split almost exactly in half between the two parties. Polls likewise show that voters divide almost evenly about a potential rematch between President Joe Biden and former President Donald Trump.
It’s premature to predict which party will emerge from the 2024 election with the upper hand. But it’s not too soon to identify the contests that will most likely function as the tipping points in 2024. Here’s my attempt to identify the places and races that will most likely decide the nation’s direction after November’s election:
The Senate
Throughout this century, the Senate has almost always teetered on a knife’s edge. In the 12 congressional sessions since 2001, one party or the other has reached a Senate majority of 55 seats only three times (Democrats in 2009 and 2013 and Republicans in 2005). Rarely since the Civil War has the Senate been so closely divided for so long a period; in the last two decades of the 20th century, for instance, one party or the other reached 55 Senate seats in seven of the 10 congressional sessions.
One big reason the Senate is now so precariously balanced is because of another fundamental change: The tightening correlation between how states vote in presidential and Senate elections. As recently as the late 20th century, ticket-splitting still was common in Senate races.
But in this century, it has become extremely difficult for either side to win many Senate seats behind enemy lines – in other words, in states that usually vote the other way for president. That trend is the most powerful force threatening Democrats’ hold on the upper chamber.
Democrats now hold 48 of the 50 Senate seats in the 25 states that Biden carried in 2020 – with Republicans Susan Collins of Maine and Ron Johnson of Wisconsin, who narrowly won reelection in 2022 – the sole exceptions. Republicans, in turn, hold 47 of the 50 Senate seats in the 25 states that voted for Trump in 2020. Democrats Sherrod Brown in Ohio, Jon Tester in Montana, and Joe Manchin in West Virginia, who is retiring, are those three exceptions.
The core of the Democrats’ Senate challenge in 2024 is that they must defend all three of those seats at a time when it appears highly likely that Trump will be on the ballot again.
Those three states aren’t the only seats that could change hands. Democrats are also defending seats in Nevada, Michigan, Pennsylvania and Wisconsin – all states that Biden won by less than 3 percentage points. (Also at stake this year is the Arizona Senate seat held by Kyrsten Sinema, a former Democrat turned independent who still caucuses with the party.) And Democrats have recruited credible challengers for uphill fights against Republican Sens. Ted Cruz and Rick Scott in Texas and Florida respectively.
If Biden can’t improve his standing before November, Republicans might flip the Senate seats in one or more of those barely Biden states. And if the bottom falls out for the GOP this year – possibly if Trump is found guilty in some of the criminal trials against him – Democrats might make a run at Florida or Texas.
But if the national environment remains closely divided between the parties, control of the Senate will likely come down to the three Democratic-held seats in Trump-won states. If no other seats change hands, Democrats can afford to surrender only one of the “Trump three” to maintain 50 Senate seats – and the possibility of maintaining control of the chamber if they also hold the White House (because of the vice president’s tie-breaking vote).
With Manchin retiring, both sides consider it virtually assured that Republicans will take West Virginia. That means both Brown and Tester will likely need to win for Democrats to reach 50 Senate seats.
Both incumbents face the common problem that Biden is highly unlikely (to put it charitably) to win their state. But of the two, Brown may have a somewhat easier path to survive anyway. The back-to-back 2023 wins for two referenda that were effectively about protecting abortion rights in Ohio shows a potential pathway for Brown to follow to a fourth term. Brown is unlikely to run as well in Trump-trending rural areas as he has in the past – especially if the former president is on the ballot. But the strong vote last year for abortion rights in the state’s biggest suburban communities, including some that have previously leaned toward the GOP, suggests Brown could overcome rural losses by improving among the white-collar voters who have moved away from the GOP almost everywhere in the Trump years.
Tester’s challenge is that his heavily rural state doesn’t have population centers comparable to Cleveland, Columbus and Cincinnati. While Brown can win even if he loses ground in rural and small-town areas, Tester probably can’t survive as much erosion. He’ll need to find ways to hold his ground against what’s likely to be gale force discontent with Biden in Montana’s more sparsely populated places.
Tester’s advantage is that Montana is a much smaller state than Ohio, and he’s established a strong personal brand as a flat-topped, dirt-under-his-fingernails embodiment of Montana traditions, down to the gun rack in his pick-up truck. “I’m defending our way of life with everything I’ve got,” he says in one ad running now.
It’s a good bet the tipping point that determines if Democrats can reach 50 Senate seats will be whether enough Montana voters agree with Tester on the same day that most of them will likely vote to replace Biden.
The House of Representatives
Compared to the Senate, the House hasn’t been closely divided as consistently through the past few decades. At times since 2000, each party has amassed comfortable House majorities.
But the House may be following the Senate into an era of smaller and less stable advantages. In each of the past two elections, first Democrats and then Republicans won a majority of only 222 seats. Since the House was enlarged to 435 seats before World War I, only once have consecutive sessions featured back-to-back majorities about that small.
One reason House majorities may be shrinking is the growing sophistication of gerrymanders, which have reduced the number of competitive seats that can switch hands from election to election, no matter the conditions in the country. But another big factor is the same dynamic pushing the Senate toward more precarious majorities: the growing inability of either side to win many seats that vote for the other party’s presidential candidates.
Just 23 House members – only about 1-in-20 – hold seats that backed the other party’s presidential candidate. That includes 17 Republicans in districts that voted for Biden in 2020 and five Democrats in seats that backed Trump. Republicans in 2022 also won an 18th congressional district that voted for Biden, but that seat is now vacant after the House recently voted to expel George Santos. The special election to replace him is scheduled for February.
Democrats will need to play defense in the five Trump seats they hold, as well as in some seats (particularly in heavily blue-collar industrial states like Michigan, Ohio and Pennsylvania) that preferred Biden only narrowly last time. A Republican-driven redrawing of the district lines in North Carolina is also guaranteed to cost Democrats several House seats.
But many operatives on both sides believe that in a close election, the struggle for control of the House will most likely come down to how many of the Republican-held Biden seats Democrats can flip. Those 18 seats are scattered across eight states, but concentrated in California (five) and New York (six) – two states Biden remains virtually certain to win in November.
In California, the biggest question for Democrats is whether they can mobilize strong turnout – and rebuild their vote margins – among the substantial non-White population in all five Republican-held Biden districts (including two in the heavily Latino Central Valley and two in Orange County, which has large Latino and Asian-American populations).
In New York, the results may depend more on the white-collar, well-educated suburban voters who have mostly drifted away from the GOP under Trump. Republicans unexpectedly bucked that trend to win multiple House seats in 2022 with a large percentage of college graduates, both on Long Island and in the Hudson River valley. That included the seats won by Republicans Anthony D’Esposito, Nick LaLota, Mike Lawler and Santos. (New York Republicans Marc Molinaro and Brandon Williams also captured Biden-won districts that are more blue-collar in nature.)
Even amid disenchantment with Biden’s record on inflation, immigration, and crime, this may be difficult terrain for Republicans to hold in the more partisan environment of a presidential year, especially if the GOP renominates Trump. The special election to replace Santos next month in a district that straddles Nassau County and Queens will offer an early measure of how New York voters in these districts are weighing their discontent about Biden with their distaste for Trump. But however that turns out, Democrats are certain to benefit from a state court-ordered redistricting process that will likely allow them to weaken several (though not all) of the Biden-district Republicans. (LaLota, for instance, represents Suffolk County, where the movement toward Trump will make it hard to draw a district better for Democrats.)
While the fight for control of the House will span a diverse nationwide battlefield, the tipping point in the struggle may come down to how many of the New York Republicans in Biden districts Democrats can dislodge.
The White House
From some angles, the presidential race doesn’t seem as closely balanced as the struggle for control of Congress. Democrats have won the popular vote in seven of the past eight presidential elections – something no party had done since the formation of the modern party system in 1828. And while Democratic presidential nominees have crossed 50% of the vote three times since 1992, George W. Bush in 2004 is the only Republican presidential nominee to win a majority of the vote since then – and he did it only barely.
But the Electoral College competition has been much tighter. In 2000 and 2016, the GOP nominee lost the popular vote but still won the Electoral College – something that had happened only three times in American history up until that point. In 2020, although Biden won the popular vote by over 7 million, a shift of just 44,000 votes in three states would have produced an Electoral College tie.
As with congressional elections, the competition for the Electoral College is so close precisely because so many states are not. Each party has carried 20 states in at least the past four presidential elections; that’s the highest percentage of states that have voted the same way in four consecutive elections since the turn of the 20th century.
That’s left a handful of truly competitive swing states to decide the outcome. Biden won in 2020 by flipping five states that had voted for Trump in 2016: Arizona and Georgia in the Sunbelt, and Michigan, Pennsylvania and Wisconsin in the industrial heartland. While the two sides will contest a few other states this year – with Republicans targeting Nevada and maybe Minnesota or New Hampshire, and Democrats besieging North Carolina – it’s most likely that a close election will be decided by those five states.
Of those five, Biden in 2020 won Arizona (0.4 points) and Georgia (0.3 points) by the smallest margins. But Trump or another Republican could win back both of those states – and for that matter Nevada – and still fall just short of the 270 Electoral College votes needed to win. “I don’t believe there is a race without GOP wins in AZ and GA,” Republican pollster Gene Ulm wrote in an email. “This isn’t the tipping point; it’s the STARTING point.”
Conversely, Biden’s best performance in 2020 among the five came in Michigan (which he won by a comfortable 2.8 points) and Pennsylvania (which provided him a narrower, but still solid, 1.2 point edge). Democrats also ran extremely well in both Michigan and Pennsylvania in 2022. Yet if Biden holds only Michigan and Pennsylvania from the big five states, he would also fall just short of 270 Electoral College votes, even if he also defends Nevada.
That leaves Wisconsin as the state that looks most likely to function as the tipping point in a close presidential race. Wisconsin itself has been achingly close in recent years: Biden in 2020 won it by only 0.6 points – after Trump had taken it in 2016 by 0.8 points. In contrast to the strong blue trend in Michigan and Pennsylvania, Wisconsin returned a characteristically mixed verdict in 2022, with Democratic Gov. Tony Evers winning reelection by only about 3 points, and Johnson surviving by just 1 point.
Wisconsin has already played the tipping point role in each of the past two presidential elections, according to calculations by Charles Franklin, director of the Marquette University Law School Poll. Franklin ranked each state from the largest margin of victory to the largest margin of defeat for both candidates. Based on that ranking, Wisconsin was the state that carried Trump across 270 Electoral College votes in 2016 – and the state that did the same for Biden in 2020.
Jim Messina, the 2012 campaign manager for Barack Obama, says that his firm’s computer modeling of potential 2024 outcomes identifies Wisconsin as the tipping point state about two-thirds of the time. “It makes sense given 2020 and how Wisconsin was the toughest [for Democrats] of all three states,” Messina wrote in an email, referring also to Michigan and Pennsylvania. “And in 2022, it was THE ONLY state where one party won the ’22 senate race but lost the ’20 presidential.”
While Michigan and Pennsylvania have tilted more toward Democrats since 2016 than Wisconsin, it’s possible that order could shift in November. The Israel-Hamas war, for instance, is threatening Biden’s support among Michigan’s Arab-American and Muslim population, which is larger than in most states.
But in the end, it still seems unlikely that Biden would win Wisconsin and lose either Michigan or Pennsylvania. Intrinsically, Wisconsin is more difficult for Democrats than the other two because of the composition of its electorate. Minorities represent a much smaller share of the total vote in Wisconsin than in Michigan or Pennsylvania, and compared to the other two, a significantly larger share of Wisconsin ballots are cast by the Whites without a four-year college degree who have become the GOP’s core constituency in the Trump era.
“If Pennsylvania and Michigan are going for Trump [or another Republican] then surely you’d expect us to do it as well,” Franklin said of his state, in a view shared by many political operatives. “Absent sort of some unexpected shift, I still see us both at that tipping point and extremely close here.”
It remains possible, of course, that either party might pull away in November for a more resounding victory than seems likely today. Bill McInturff, the veteran GOP pollster, and Stu Stevens, a long-time GOP strategist who has become a fierce critic of the Trump-era party, both think this year ultimately might resemble the 1980 race between President Jimmy Carter and Ronald Reagan. That was close in polls for most of the campaign but then broke decisively toward Reagan at the end.
Stevens thinks that if there is a break this year it will most likely come against Trump, if he’s the nominee, while McInturff has stressed the weakness of Biden’s polling compared to other recent presidents beginning their reelection year. Collapse always remains a possibility for two candidates whose flaws often look more apparent than their strengths.
But with so many voters now motivated more by distaste for the other party than support for their own, the reciprocal antipathy of red and blue America virtually guarantees another election that leaves the country split in half – and nervously watching as its course is determined by a few tightly contested tipping-point races.
