Democrats on Thursday seized on a new report citing unredacted emails that bolster the case that President Trump was directly involved in withholding military aid to Ukraine as he was seeking investigations that could benefit his reelection bid.

House Speaker Nancy Pelosi (D-Calif.) joined Senate Minority Leader Charles E. Schumer (D-N.Y.) in pressing for key witnesses and documents to be included in a Senate impeachment trial of Trump following the report.

Senate leaders remained at an impasse Thursday over the scope of a trial, and aides to Schumer and Senate Majority Leader Mitch McConnell (R-Ky.) said the two men had not spoken over the holidays about the standoff. Pelosi has held off sending the articles of impeachment — alleging abuse of power and obstruction of Congress — to the Senate as Democrats seek guarantees about witnesses and documents that will be subpoenaed regarding Trump’s conduct toward Ukraine.

The report by Kate Brannen, published by Just Security, referenced an email from Michael Duffey, associate director of national security programs at the Office of Management and Budget, to Elaine McCusker, the acting Pentagon comptroller, on Aug. 30, a little more than a month after Trump pressed Ukrainian President Volodymyr Zelensky for investigations during a phone call.

In the email, which followed a meeting with Trump that included senior administration officials, Duffey told McCusker, “Clear direction from POTUS to hold.”

A redacted version of that email — and several others cited in the report by Brannen, a veteran Pentagon reporter — had previously been made public as the result of Freedom of Information Act litigation.

“The newly-revealed unredacted emails are a devastating blow to Senator McConnell’s push to have a trial without the documents and witnesses we’ve requested,” Schumer said in a statement Thursday. “These emails further expose the serious concerns raised by Trump administration officials about the propriety and legality of the president’s decision to cut off aid to Ukraine to benefit himself.”

Schumer has sought guarantees from McConnell that several administration officials who declined to participate in House impeachment proceedings will be subpoenaed to testify in a Senate trial, including acting White House chief of staff Mick Mulvaney, former national security adviser John Bolton and Duffey. McConnell has said the Senate should decide on what if any witnesses to call after hearing opening statements from House impeachment managers and Trump’s lawyers.

Schumer said the unredacted emails raise “questions that can only be answered by having the key Trump administration officials . . . testify under oath in a Senate trial.”

“The American people deserve a fair trial that gets to the truth, not a rigged process that enables a cover-up,” Schumer said.

Schumer has also continued efforts in private to step up pressure on Senate Republicans over the structure of a Senate impeachment trial. The minority leader convened a conference call with Democratic senators on Tuesday, when he said the string of new revelations about Trump and the administration’s Ukraine dealings bolstered their public case to demand witnesses and documents as part of the Senate proceedings, according to a Democratic aide familiar with the call.

He plans to be in Washington on Friday to deliver a rebuttal to a speech expected from Senate Majority Leader Mitch McConnell (R-Ky.) about impeachment, according to the aide, who spoke on the condition of anonymity to read out a private caucus conversation.

At the heart of the Democrats’ case is the allegation that Trump tried to leverage a White House meeting and $391 million in congressionally appropriated military aid, sought by Ukraine to combat Russian military aggression, to pressure Zelensky to launch an investigation of former vice president Joe Biden, a 2020 presidential candidate, and his son Hunter Biden, as well as a probe of an unfounded theory that Kyiv conspired with Democrats to interfere in the 2016 presidential election.

In a tweet, Pelosi said, “Trump engaged in unprecedented, total obstruction of Congress, hiding these emails, all other documents, and his top aides from the American people. His excuse was a phony complaint about the House process. What’s the excuse now? Why won’t Trump & McConnell allow a fair trial?”

House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) said in a statement that the messages show that the White House “cannot argue that the aid was held for any reason other than to pressure Ukraine into helping the President’s re-election efforts.”