David Axelrod sits backstage with then-US Sen. Barack Obama during a 2007 campaign rally for Obama's presidential run. Axelrod, a senior political commentator for CNN, was a senior adviser for Obama during his presidency.
David Axelrod sits backstage with then-US Sen. Barack Obama during a 2007 campaign rally for Obama's presidential run. Axelrod, a senior political commentator for CNN, was a senior adviser for Obama during his presidency.
Jim Young/REUTERS/Newscom
Obama huddles with his campaign staff, including Robert Gibbs, right, before a town-hall meeting in Erie, Pennsylvania, in April 2008. Gibbs would later be Obama's press secretary.
Obama huddles with his campaign staff, including Robert Gibbs, right, before a town-hall meeting in Erie, Pennsylvania, in April 2008. Gibbs would later be Obama's press secretary.
Charles Ommanney/Getty Images
Obama and Axelrod, trailed by aide Reggie Love, talk backstage before a town-hall meeting in Raleigh, North Carolina, in April 2008.
Obama and Axelrod, trailed by aide Reggie Love, talk backstage before a town-hall meeting in Raleigh, North Carolina, in April 2008.
Charles Ommanney/Getty Images
Obama talks on the phone aboard his plane as members of the campaign travel to St. Paul, Minnesota, in June 2008.
Obama talks on the phone aboard his plane as members of the campaign travel to St. Paul, Minnesota, in June 2008.
Jason Reed/REUTERS/Newscom
Obama and Axelrod sit on an airport tarmac in Washington in June 2008.
Obama and Axelrod sit on an airport tarmac in Washington in June 2008.
Jim Young/REUTERS/Newscom
Obama and Axelrod hug at the 2008 Democratic National Convention, where Obama had officially received the party's nomination for president.
Obama and Axelrod hug at the 2008 Democratic National Convention, where Obama had officially received the party's nomination for president.
Charles Ommanney/Getty Images
Axelrod and White House Chief of Staff designate Rahm Emanuel listen to Obama speak at a news conference in Chicago in December 2008.
Axelrod and White House Chief of Staff designate Rahm Emanuel listen to Obama speak at a news conference in Chicago in December 2008.
Charles Dharapak/AP
Obama speaks with aides in the White House Oval Office in February 2009. From left are Senior Advisor Pete Rouse, White House Director of Legislative Affairs Phil Schiliro, Axelrod, National Economic Council Director Lawrence Summers and Emanuel.
Obama speaks with aides in the White House Oval Office in February 2009. From left are Senior Advisor Pete Rouse, White House Director of Legislative Affairs Phil Schiliro, Axelrod, National Economic Council Director Lawrence Summers and Emanuel.
Pete Souza/White House Photo
Obama, Axelrod and Gibs tour the Great Pyramids of Giza during a trip to Egypt in 2009.
Obama, Axelrod and Gibs tour the Great Pyramids of Giza during a trip to Egypt in 2009.
MANDEL NGAN/AFP/Getty Images
Obama laughs with aides aboard Air Force One in November 2009.
Obama laughs with aides aboard Air Force One in November 2009.
Pete Souza/White House Photo/Newscom
Axelrod and Obama attend a meeting with congressional leadership in July 2010.
Axelrod and Obama attend a meeting with congressional leadership in July 2010.
SAUL LOEB/AFP/Getty Images
Obama works on an acceptance speech with Axelrod and Director of Speechwriting Jon Favreau, center, on the night of the 2012 election.
Obama works on an acceptance speech with Axelrod and Director of Speechwriting Jon Favreau, center, on the night of the 2012 election.
The White House/Getty Images
Obama and Axelrod sit together in the White House as they tape a podcast for the <a href="index.php?page=&url=http%3A%2F%2Frss.cnn.com%2Fservices%2Fpodcasting%2Faxe%2Frss" target="_blank">"Axe Files"</a> in December 2016.
Obama and Axelrod sit together in the White House as they tape a podcast for the "Axe Files" in December 2016.
Gabriella Demczuk for CNN