WASHINGTON — Speaker Nancy Pelosi quietly laid the groundwork on Thursday to send impeachment articles against President Trump to the Senate, indicating that the House would “soon” end a weekslong impasse and vote to bring the charges to trial.
Though the speaker offered no specific timetable for her decision, lawmakers and aides said the House could move toward a vote next week before lawmakers decamp for a weeklong recess. They braced for an announcement from Ms. Pelosi about her plans as soon as Friday, as senators made final preparations for what would be the third presidential impeachment trial in American history.
But on Thursday, even as pressure continued from Senator Mitch McConnell, Republican of Kentucky and the majority leader, and from some Democrats to quickly send the charges, Ms. Pelosi would not reveal her plans.
“I will send them over when I’m ready,” Ms. Pelosi said at her weekly news conference on Thursday morning, “and that will probably be soon.”
The speaker reiterated a call for Mr. McConnell to detail the rules for a Senate trial so she could choose a team of lawmakers best suited to prosecute the articles of impeachment against Mr. Trump, for abuse of power and obstruction of Congress.
“I keep giving you the same answer,” she told reporters who questioned her about when she would act. “As I said right from the start, we need to see that the arena in which we’re sending our managers. Is that too much to ask?”
By Thursday evening, Mr. McConnell effectively said that it was.
“No, we’re not going to do that,” he told reporters as he left the Capitol. Earlier, he warned his members to be prepared to plunge in the coming days into the unknown of a proceeding that could tie up the Senate for weeks.
And in a bid to signal to Ms. Pelosi that her time was running out, Mr. McConnell signed on to a resolution introduced by Senator Josh Hawley, Republican of Missouri, that would alter Senate rules to allow the impeachment charges to be dismissed without a trial if they are not delivered within 25 days of House approval.
The statements from the two leaders suggested that a bitter confrontation between Democrats and Republicans over the shape of the coming trial, while not exactly abating, may soon move off center stage.
The Democratic-led House impeached Mr. Trump in the days before Christmas. But the speaker elected not to immediately send the articles of impeachment to the Senate, in a bid to pressure the Republican-led chamber into allowing additional witnesses and documents Mr. Trump blocked during the House’s three-month inquiry.
Without them, Democrats have argued, the trial will be fundamentally tainted and effectively continue a cover-up they say Mr. Trump has directed from the start.
“Witnesses, facts, truth — that’s what they’re afraid of,” Ms. Pelosi said of Senate Republicans.
Ms. Pelosi’s comments came in the face of a spate of calls to deliver the charges from lawmakers in both parties. Earlier Thursday morning, before Ms. Pelosi spoke to reporters, a senior Democrat from Washington became the first House chairman to publicly urge the speaker to move on, only to backtrack.
“I think it is time to send the impeachment to the Senate and let Mitch McConnell be responsible for the fairness of the trial,” Representative Adam Smith, who leads the House Armed Services Committee, said on CNN.
But in a sign of Ms. Pelosi’s firm hold on her caucus, Mr. Smith soon walked backed the comments in a post on Twitter, saying that he “misspoke.” He deferred to Ms. Pelosi if she believed that continuing to withhold the articles would “help force a fair trial in the Senate.”
A handful of Democratic senators who had previously made similar statements likewise amended their remarks on Thursday to defer to the speaker.
Unmoved, Mr. McConnell said this week that he had secured the votes necessary to begin a trial on his own terms, without an agreement on hearing from witnesses or admitting new evidence. Mr. McConnell has said he will work in concert with Mr. Trump’s legal team to bring about a speedy acquittal in the Senate, after a House impeachment proceeding he has condemned as unfair and based on a shoddy case.
In remarks of his own on Thursday, Mr. McConnell compared the speaker’s approach to “junior-varsity political hostage situations.”
“This is what they have done,” he said before Ms. Pelosi spoke. “They have initiated one of the most grave and most unsettling processes in our Constitution and then refused to allow a resolution.”
At the White House, Mr. Trump appeared eager for the proceeding to get underway. He posted to Twitter to accuse Ms. Pelosi of balking because she had no case against him, saying that the articles “show no crimes and are a joke and a scam!”
Speaking at an environmental event a short time later, Mr. Trump said he would leave it to the Senate to determine whether to call witnesses at the trial, but proceeded to offer his own wish list at odds with that of Democrats.
“I’d like to hear the whistle-blower,” Mr. Trump said. “I’d like to hear Shifty Schiff. I’d like to hear Hunter Biden and Joe Biden.”
The targets were familiar ones. The whistle-blower is an anonymous C.I.A. employee whose complaint about Mr. Trump’s pressure campaign on Ukraine prompted the House impeachment inquiry. Representative Adam B. Schiff of California led that inquiry as chairman of the House Intelligence Committee and is likely to lead the chamber’s prosecutorial team at trial.
And it was the Bidens who got Mr. Trump into impeachment jeopardy in the first place when he pressed Ukraine’s leader to investigate the former vice president and his son, along with other Democrats. The House’s investigation found that Mr. Trump ultimately used nearly $400 million in security assistance and a White House meeting as leverage to push Ukraine to publicly announce those targets of scrutiny.
Taking her turn in what has become a daily rhetorical fight with Mr. McConnell, Ms. Pelosi accused the Republican leader of trying to cover up the facts of the case in a rush to acquit Mr. Trump.
She rejected his insistence that the Senate would proceed just as it did in 1999, when it tried President Bill Clinton for high crimes and misdemeanors.
Then, the speaker noted, all 100 senators agreed to procedures to start the trial. This time, Mr. McConnell is muscling ahead without an agreement with Democrats who want a guarantee that the trial will include witnesses and new evidence.
Democrats have asked to hear from several of Mr. Trump’s top aides whom he succeeded in blocking from House investigators, including the acting White House chief of staff, Mick Mulvaney, and John R. Bolton, the president’s former national security adviser.
Still, Ms. Pelosi said on Thursday that her holdout had now merely come down to hearing in detail what Mr. McConnell had planned for the rules. His aides have suggested that the speaker need only look at those adopted by the Senate in the Clinton trial.
“All we want to know is what are the rules,” Ms. Pelosi said. “It doesn’t mean we have to agree to the rules or we have to like the rules. We just want to know what they are.”
Aides said Ms. Pelosi had yet to complete her team of prosecutors, called managers. Mr. Schiff and Representative Jerrold Nadler of New York, the Judiciary Committee chairman, will almost certainly lead it. But Ms. Pelosi is also looking to build a racially and geographically diverse team best equipped to move senators.