WASHINGTON >> Senate Majority Leader Mitch McConnell said today there will be “no haggling” over the process for President Donald Trump’s impeachment trial in a deepening standoff with House Speaker Nancy Pelosi over Democratic demands for details and more witnesses.

McConnell has indicated Republicans have the leverage they need to launch Trump’s trial on his terms, but Pelosi’s reluctance to transmit the articles of impeachment leaves the Senate proceedings at a standstill.

A resolution is expected this week in the showdown that is testing the negotiating skills of the two seasoned leaders as they face off over the rare impeachment trial, only the third in the nation’s history.

The House impeached Trump last month on charges that he abused the power of his office by pressuring Ukraine’s new leader to investigate Democrats, using as leverage $400 million in military assistance for U.S. ally as it counters Russia at its border. The funding for Ukraine was eventually released but only after Congress intervened.

Trump insists he did nothing wrong. His trial will be conducted in the Senate, where Republicans have a thin majority.

“There will be no haggling with the House over Senate procedure,” said McConnell, R-Ky. “We will not cede our authority to try this impeachment. The House Democrats’ turn is over.”

But even as McConnell spoke from the Senate floor, Pelosi, D-Calif., was giving no indication of her plans. In a closed-door meeting with the House Democratic caucus, she spoke instead about the crisis in the Middle East, with Iran’s retaliatory ballistic missile attacks on U.S. bases in Iraq, according to several Democrats in the room.

Pelosi wants McConnell to “immediately” make public the details of his trial proposal, according to a letter to colleagues. She wants to see how much time will be devoted to the trial, and other details before she announces her choice of House managers to try the case in the Senate, according to Democrats familiar with the situation and granted anonymity to discuss it.

“Sadly, Leader McConnell has made clear that his loyalty is to the President and not the Constitution,” Pelosi wrote to colleagues late Tuesday. She said the process he is outlining “is not only unfair but designed to deprive Senators and the American people of crucial documents and testimony.”

The contours of a Senate trial have been in dispute for weeks. But McConnell gained ground when he announced Tuesday that he has support from the majority of senators to start a trial structured like the last one, against President Bill Clinton in 1999. Those proceedings also began without an agreement on witnesses.

“We have the votes,” McConnell told reporters.

It takes 51 votes for agreement on the trial proceedings, and with Republicans holding a 53-47 Senate majority, Democrats are trying to peel off support from a few GOP senators for their demands.

McConnell, who has resisted calling new witnesses, expects a speedy trial that will end with Trump acquitted of the charges. He complained about Pelosi’s “‘endless appetite for these cynical games” and said it will be up to senators to decide if they want more testimony.

On the Senate floor today, Democratic leader Chuck Schumer promised he would force votes on witnesses, requiring senators to choose whether they want to hear from Trump former national security adviser John Bolton and others.

“When the Senate has votes on witnesses and documents, my Republican colleagues will have to answer to not just the president,” Schumer said. “The American people do not want a cover up.”

Pelosi, who is delaying transmission of the articles as Democrats press for testimony and documents, told House leaders in a private meeting Tuesday that she believed the strategy was working, according to those in that meeting.

“People are united,” said Democratic Rep. Mike Thompson of California about the mood in the House caucus.

Republicans countered that Democrats rushed to impeach and then delayed the process. Pelosi has yet to choose House impeachment managers for the trial, a politically sensitive next step, with many lawmakers vying to be candidates.