WASHINGTON (Reuters) - U.S. House Speaker Nancy Pelosi said House Democrats will determine on Tuesday when to send formal impeachment charges against President Donald Trump to the Senate and warned that Republicans will pay a political price for denying a trial with witnesses.

Pelosi, speaking on Sunday on ABC’s “This Week” program, said her caucus at a regular meeting on Tuesday morning would vote on the timing of sending articles of impeachment to the Senate and naming trial managers in the House.

“I have always said I would send them over. So there

shouldn’t be any mystery to that,” Pelosi said.

Pelosi has delayed delivery of the charges for weeks to compel Senate Majority Leader Mitch McConnell to agree to include new witness testimony and evidence about Trump’s pressure on Ukraine to probe former Vice President Joe Biden, a leading Democrat running for the nomination to face Trump in the November election.

Her gambit appeared to fail as McConnell slammed the door on that idea last week, saying he had enough Republican votes to start the trial without a commitment to hear from additional witnesses, including former Trump national security adviser John Bolton.

Bolton has said he would be willing to testify if subpoenaed by the Senate.

Pelosi insisted her delay helped make American voters aware of the need for a “fair trial” with witness testimony and evidence. If McConnell continues to block such proceedings, Republicans would pay a political price.

“I think that he will be accountable to the American people for that,” Pelosi said.

The Senate, where Trump’s Republican party holds a majority, is widely expected to acquit Trump of the charges, as no Republicans have voiced support for ousting him, a step that would require a two-thirds majority.

Nonetheless, Democrats want a longer trial that turns up more information about Trump’s efforts to pressure Ukrainian President Volodymyr Zelenskiy to open a Biden probe, including a July 25 phone call between the leaders. As the 2020 U.S. presidential campaign heats up, they believe this will turn some voters against Trump.

The Democratic-controlled House, in a party-line vote, impeached Trump on Dec. 18 on charges of abusing power and obstructing Congress. Trump says he did nothing wrong and has dismissed his impeachment as a partisan bid to undo his 2016 election win.

Trump sent several tweets on Sunday criticizing Pelosi and the Democratic-led impeachment effort.

“This phony Impeachment Hoax should not even be allowed to proceed. Did NOTHING wrong. Just a partisan vote. Zero Republicans. Never happened before!” Trump said on Twitter.