President Donald Trump on Monday decried House Speaker Nancy Pelosi's call for "fairness" in a Senate trial as both chambers of Congress remain at a stalemate over the next steps in his impeachment.

The comment came as the Republican and Democratic Senate leaders pushed forward with their cases for the trial process.

"Pelosi gives us the most unfair trial in the history of the U.S. Congress, and now she is crying for fairness in the Senate, and breaking all rules while doing so," Trump tweeted Monday morning. "She lost Congress once, she will do it again!"

Trump tweeted shortly after Pelosi, D-Calif., posted that the House "cannot choose our impeachment managers until we know what sort of trial the Senate will conduct."

"President Trump blocked his own witnesses and documents from the House, and from the American people, on phony complaints about the House process," she tweeted. "What is his excuse now?"

Trump, who's on vacation in Florida, went on the offensive against Pelosi again later Monday.

"What right does Crazy Nancy have to hold up this Senate trial. None! She has a bad case and would rather not have a negative decision. This Witch Hunt must end NOW with a trial in the Senate, or let her default & lose. No more time should be wasted on this Impeachment Scam!" he tweeted.

Pelosi has said she does not intend to transmit the articles over to the Senate until Senate Majority Leader Mitch McConnell, R-Ky., announces the process by which the chamber will conduct the trial.

As it stands, McConnell has said he wants the Senate to conform to the precedent set in 1999, during then-President Bill Clinton's impeachment trial, which included a two-resolution process: first, an initial agreement to first hear the case and then a later vote on whether to call witnesses.

McConnell's counterpart, Senate Minority Leader Chuck Schumer, D-N.Y., has pushed for a single resolution that would set parameters for presenting the case and allow for the calling of witnesses. Schumer has said he wants the Senate to call former national security adviser John Bolton and acting White House chief of staff Mick Mulvaney, as well as two others, as witnesses to testify about Trump’s conduct toward Ukraine.

Speaking with "Fox and Friends" on Monday, McConnell said "we're at an impasse" and "we can't do anything until the speaker sends the papers over, so everybody enjoy the holidays."

McConnell blasted Pelosi for trying to "tell us how to run the trial."

"Look, what we need to do is to listen to the arguments, have a written questioning period, and then decide whether we need witnesses or not," McConnell said, adding that some Republican senators "have said, 'I am thinking of myself as a juror,'" while others believe "the case against President Trump is very thin."

Speaking at a press conference Sunday, Schumer said the Senate "is yearning to give President Trump due process, which means that documents and witnesses should come forward."

"What is a trial with no witnesses and no documents?" he said. "It's a sham trial. And that's why we feel so strongly that there ought to be witnesses and documents."

He pledged the trial would "be very, very fair."

The House approved two articles of impeachment against Trump last week. The first charged the president with abusing his power by pushing Ukraine to probe former Vice President Joe Biden, his son Hunter and Democrats while withholding nearly $400 million in military aid to the country, as well as an official White House visit for Ukrainian President Volodymyr Zelenskiy. The second article charged Trump with obstructing Congress' efforts to probe those efforts.

This weekend, newly released emails showed that a request to withhold Ukrainian military aid came less than two hours after Trump's July 25 phone call with Zelenskiy, which is at the center of the impeachment proceedings.

Schumer said those documents show "how important having these witnesses are."

On Monday, he sent a letter to senators outlining the "need" for the Senate to receive and review documents from the Trump administration as senators weigh impeachment.

McConnell "still hasn’t answered the question — what is wrong with witnesses, what is wrong with documents?" Schumer told reporters later on Monday. "They're afraid of the truth."