Rep. Adam Schiff (D-Calif.) said former national security adviser John Bolton "refused" to submit an affidavit on his take of President Trump's "Ukraine misconduct" when asked by House Democrats.

The House Intelligence Committee chairman told MSNBC's Rachel Maddow on Wednesday that Democrats had approached Bolton's counsel after the Senate voted last week not to include any additional witnesses or documentation in the impeachment trial.

"We did approach John Bolton's counsel, asked if Mr. Bolton would be willing to submit an affidavit under oath, describing what he observed in terms of the president's Ukraine misconduct, and he refused," Schiff told Maddow. "For whatever reason, he apparently was willing to testify before the Senate, but apart from that, seems intent on saving it for his book."

The California Democrat did reiterate that "absolutely" no decision has been made about whether the House will subpoena the former adviser following the Senate's acquittal of the president Wednesday.

The Hill has reached out to Bolton's counsel for comment.

The Senate voted to acquit the president of two articles of impeachment Wednesday after Senate Democrats did not get enough votes to request more witnesses in the trial.

Democrats had wanted Bolton to testify in front of the upper chamber after he announced he would be willing to if subpoenaed.

The New York Times reported in the days before the vote on witnesses that Bolton's upcoming book would include a claim that Trump wanted to withhold military assistance from Ukraine until the country agreed to investigate former Vice President Joe Biden. Previously, the president's lawyers had argued that Trump did not tie the delay in aid to the desired Biden investigations.

House Democrats had requested that Bolton testify during their impeachment inquiry, but the former adviser declined after the White House did not allow him to appear as a witness, and the House was unwilling to wait for the matter to be resolved in the courts.

House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) said Wednesday ahead of the president's acquittal that the House would "likely" subpoena Bolton.