Former President Jimmy Carter Jimmy CarterTexas Democrats roll out first wave of planned digital ads as Election Day nears Chris Matthews ripped for complimenting Trump's 'true presidential behavior' on Ginsburg Warning signs flash for Lindsey Graham in South Carolina MORE (D) on Tuesday called out the White House for "trying to stonewall" the House Democrats' impeachment inquiry, saying that blocking administration officials' testimony would only serve as more evidence against President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE.

Carter, who served as president between 1977 and 1981, was asked on MSNBC if the White House was right to block key officials' testimony.

He replied that he thinks the "fact that the White House is trying to stonewall and not provide adequate information" is a "departure from custom and ... what American people expect."

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“I think that’s going to be another item of evidence used against [Trump] if he continues to stonewall and prevent evidence to be put forward to the House and Senate to consider," Carter added, before advising Trump to "tell the truth" and "cut back on his Twitter feed" amid the congressional inquiry.

A wave of revelations regarding Trump's interactions with Ukrainian President Volodymyr Zelensky led Speaker Nancy Pelosi Nancy PelosiDemocratic senator to party: 'A little message discipline wouldn't kill us' Overnight Health Care: New wave of COVID-19 cases builds in US | Florida to lift all coronavirus restrictions on restaurants, bars | Trump stirs questions with 0 drug coupon plan Overnight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds MORE (D-Calif.) to announce a formal impeachment inquiry last month. As part of the inquiry, chairmen of multiple House committees have called for testimony and documents from several officials with ties to the president's dealings with Ukraine, setting up a contentious battle with the administration.

European Union Ambassador Gordon Sondland was expected to privately testify before Congress on Tuesday. Just hours before his scheduled deposition, the State Department ordered Sondland not to appear.

Democrats are interested in speaking with Sondland about his role in the president's effort to encourage Ukraine to investigate former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and his son over unfounded allegations of corruption.

Schiff claimed that the messages were "deeply relevant" to the impeachment inquiry and that the Trump administration's failure to allow the witnesses to testify was "strong evidence of obstruction."