Top US Democrat Nancy Pelosi said on Sunday that she believes the impeachment hearings against Donald Trump produced "enough testimony to remove him from office" when the case moves to the Senate.Speaker Pelosi will meet with the House Democratic caucus early on Tuesday to prepare for the formal vote required to send the two articles of impeachment passed by the House on to the Senate, as early as this week.The Senate trial is expected to be held quickly, with Republicans holding enough votes to easily dismiss the charges of abuse of power and obstruction of Congress. Pelosi has withheld the articles since the House impeached Trump on December 18 over allegations that he improperly pressured Ukraine to investigate his potential 2020 election rival Joe Biden, and obstructed the subsequent congressional probe.Pelosi had hoped to pressure Senate Republican leader Mitch McConnell to agree to allow witnesses and new evidence in the trial.He has not budged, however.Still, she said Sunday that the delay had accomplished important things. "We wanted the public to see the need for witnesses," she told ABC."Now the ball is in their court, to either do that or pay a price for not doing it."During the interim, she added, new emails supporting the charges against Trump had emerged, and former national security adviser John Bolton had announced his willingness to testify if subpoenaed.'There will be no haggling'If the Senate fails to subpoena Bolton - and Trump said Friday in an interview on Fox that he might invoke executive privilege to block Bolton's testimony - Pelosi said it was "not excluded" that the House might then move to subpoena him.But McConnell made clear recently he had sufficient Republican votes to ignore the Democrats' demands on witnesses and evidence.Trump, for his part, has said he expects rapid exoneration and wants to move past the trial as quickly as possible."Why should I have the stigma of Impeachment attached to my name when I did nothing wrong," the president tweeted on Sunday. "Very unfair to tens of millions of voters!" Why should I have the stigma of Impeachment attached to my name when I did NOTHING wrong? Read the Transcripts! A totally partisan Hoax, never happened before. House Republicans voted 195-0, with three Dems voting with the Republicans. Very unfair to tens of millions of voters!— Donald J. Trump (@realDonaldTrump) January 12, 2020 He also renewed a call for Democrat Adam Schiff, who led the House impeachment probe, to be called as a witness - this time also demanding that Pelosi herself be made to testify.He later said the case should be dismissed without trial, as any hearings would give undue credibility to the "witch hunt" against him. Many believe that by the Senate giving credence to a trial based on the no evidence, no crime, read the transcripts, “no pressure” Impeachment Hoax, rather than an outright dismissal, it gives the partisan Democrat Witch Hunt credibility that it otherwise does not have. I agree!— Donald J. Trump (@realDonaldTrump) January 12, 2020 The timing of the trial is critical, with political temperatures rapidly rising in this presidential election year. The first vote of the Democratic nomination process, in Iowa, is just weeks away, on February 3.Five of the candidates - Bernie Sanders, Elizabeth Warren, Amy Klobuchar, Cory Booker and Michael Bennet - are US senators, and are required to sit as jurors during the impeachment trial, curtailing their campaigning efforts.