Washington CNN  — 

Ex-national security adviser John Bolton’s announcement Monday that he would be willing to testify if the Senate subpoenaed him as part of its impeachment trial sent top White House aides scrambling, multiple people familiar with the reaction told CNN.

Shortly after Bolton’s statement was released, aides who have been tasked with handling Trump’s impeachment strategy met to discuss how to handle the situation, speculating about what Bolton’s ultimate strategy could be.

They decided against issuing a public statement, instead choosing to focus on how House Speaker Nancy Pelosi has yet to send the articles of impeachment to the Senate.

“The articles of impeachment haven’t even been sent to the Senate yet, so we can’t even start talking about who or if people will testify, if John Bolton or anybody else will be a witness,” press secretary Stephanie Grisham said on Fox News Tuesday.

The advisers also urged President Donald Trump not to comment on the matter either, though they cautioned that’s not always within their control.

But despite deflections from staff, Trump hasn’t remained entirely silent on Bolton’s potential testimony. He retweeted a Washington Examiner correspondent’s argument about Bolton Monday evening, in what may have been a sign of what’s to come if Bolton is subpoenaed.

“The White House can assert executive privilege. It’s not Bolton’s privilege; it’s the president’s. If executive privilege covers anything, it is a talk between president and top adviser on matters of foreign policy,” the tweet said.

Trump largely took a pass when asked about Bolton on Tuesday, saying it was up to lawyers and the Senate – though he worked in a dig – despite Bolton having firsthand knowledge of the hold on the aid to Ukraine, which lies at the heart of the impeachment trial.

“He would know nothing about what we’re talking about,” Trump said.

White House officials spent the rest of Monday keeping an eye on comments from the key senators who could play a critical role in deciding whether Bolton appears.

On Capitol Hill, congressional Republicans’ next move in light of Bolton’s announcement remains unclear.

Senate Majority Leader Mitch McConnell relayed to Republicans on Tuesday that he has the votes to set up ground rules for the impeachment trial, even though articles of impeachment have yet to be sent to the Senate by Pelosi.

Democrats want a deal up front to hear from witnesses and get documents, but McConnell says those matters, like Bolton’s testimony, should be dealt with later.

When asked specifically if he would vote to subpoena Bolton, Texas Republican Sen. John Cornyn said: “I’m not going to tell you how l’m going to vote on something that hasn’t happened yet.”

“We’ll cross that bridge when we get there,” said John Thune, the No. 2 Senate Republican.

“We’ll see,” Pennsylvania Republican Sen. Pat Toomey remarked.

But Utah Republican Sen. Mitt Romney took a different approach to Bolton’s potential testimony. He told CNN on Monday that he’d “like to hear what he has to say.”

However, Romney stopped short of calling for Bolton to be subpoenaed.

CNN’s Manu Raju and Phil Mattingly contributed to this report.