WASHINGTON — The outlines of President Trump’s impeachment trial began to take shape on Tuesday, as the House announced a vote to send its impeachment charges to the Senate and leaders there cautioned that the tribunal would not begin in earnest until after the holiday weekend.

Speaker Nancy Pelosi made the first move, announcing Tuesday morning that after a monthlong delay, the House would vote on Wednesday to appoint the team of lawmakers, known as managers, to prosecute the case against Mr. Trump and transmit the articles to the Senate for trial.

“The American people deserve the truth, and the Constitution demands a trial,” she said. The speaker said she would announce the names of her managers at 10 a.m. Wednesday.

In the Senate, Mitch McConnell, Republican of Kentucky and the majority leader, indicated that senators would be ready to receive the articles on Wednesday and take sworn oaths to render “impartial justice” in the trial shortly thereafter, if not the following day.

He said the Senate would put off considering the terms of the trial or the substance of the case until next Tuesday, allowing lawmakers time to vote late this week on a resolution to limit Mr. Trump’s war-making power against Iran and to approve Mr. Trump’s new trade agreement with Canada and Mexico. Senators also hope to travel home this holiday weekend because the trial requires them to remain at their desks in the Senate chamber six days a week.

“We hope to be able to achieve that by consent, which would set us up to begin the actual trial next Tuesday,” Mr. McConnell told reporters Tuesday afternoon.

The announcements paved the way for an elaborate, choreographed exchange between the two chambers to unfold on Wednesday as they look toward the third presidential impeachment trial in American history. With little precedent to guide them, House and Senate leaders were working with Chief Justice John G. Roberts Jr., who will preside over the trial, to nail down the timing of what was to come.

If all goes according to plan, the trial would begin almost a month to the day after the House voted to impeach Mr. Trump for abuse of power and obstruction of Congress, charges that stemmed from his efforts to pressure Ukraine to investigate his political opponents, then stonewall the House inquiry into his actions.

“We’ve been ready for a long time,” Eric Ueland, Mr. Trump’s congressional liaison, told reporters in the Capitol after huddling with Senate Republicans over lunch. “We could have started the morning after the House vote in December. We’re good to go, and we’re ready to go, and we’d be shocked if the House isn’t ready to go either.”

Mr. Trump’s campaign was already capitalizing on what promises to be a brutally partisan proceeding, circulating a fund-raising appeal signed by the president that announced, “We’re taking this fight to the Senate,” and asked supporters to donate to an “Emergency 2020 Impeachment Defense Fund.”

Behind the scenes, Mr. Trump’s team was bracing for a potentially damaging period, inviting conservative activists to the White House to plot strategy for the coming trial fight.

Lawmakers were anxious, too, as they moved toward an unpredictable process that will test an already strained Senate, consuming lawmakers for weeks or longer. Debates raged in public and private over difficult questions that may darken the proceeding, including whether to call witnesses and compel new evidence or to consider a motion, endorsed by Mr. Trump but opposed by Republican leaders, to quickly dismiss the charges against him with no arguments or deliberations.

Mr. McConnell used an extended Republican luncheon to brief lawmakers on protocols and procedures. He downplayed Mr. Trump’s apparent enthusiasm for a motion to dismiss, insisting it was not viable.

“There is little to no sentiment in the Republican Conference for a motion to dismiss,” Mr. McConnell told reporters after the lunch. “Our members feel that we have an obligation to listen to the arguments.”

Mr. McConnell predicted that he still had the Republican votes to set rules for the trial next week that would put off a debate over calling witnesses until after opening arguments and senatorial questioning is complete.

“All 53 or us have reached an understanding very, very similar to the one that was achieved at the beginning of the Clinton impeachment trial,” Mr. McConnell said, referring to the 1999 trial of President Bill Clinton.

Democrats argue that a trial without witnesses and new evidence would be a sham. Mr. Trump blocked the House from gaining access to both during its impeachment inquiry.

“Do Senate Republicans want to break that lengthy historical precedent by conducting the first impeachment trial of a president in history with no witnesses?” Senator Chuck Schumer of New York, the Democratic leader, asked on Tuesday.

In her statement, Ms. Pelosi accused Mr. McConnell and Mr. Trump of working together to cover up the facts the House had unearthed.

“The American people will fully understand the Senate’s move to begin the trial without witnesses and documents as a pure political cover-up,” she said. “Leader McConnell and the president are afraid of more facts coming to light.”

Still uncertain is precisely when the House managers will ceremonially walk the articles of impeachment from the House chamber to the Senate. When they do, they will formally present the articles and read them aloud in their entirety, beginning the trial.

Representative Steny H. Hoyer of Maryland, the No. 2 House Democrat, told reporters that the House vote would take place in the afternoon on Wednesday, but the procession across the Capitol could be postponed until Thursday to avoid interfering with a ceremony previously scheduled for Wednesday in the Capitol Rotunda.

After the procession, the chief justice will travel from the Supreme Court across the street to the Senate chamber to administer the oath to senators.

The team of managers is likely to be led by Representative Adam B. Schiff of California, the chairman of the Intelligence Committee who spearheaded the House’s Ukraine inquiry.

During the meeting on Tuesday, Mr. Schiff laid out his expectations for trial procedures, telling members that House managers would likely have 24 hours to present their case against Mr. Trump, spread over four six-hour days. The president's lawyers would be given the same amount of time.

Mr. Schiff’s presentation appeared to be based on the procedures from Mr. Clinton’s impeachment trial in 1999. Mr. McConnell has said he plans to adopt similar procedures this time, but he has yet to release a detailed proposal, leaving the House in the dark.

“None of us have been through it before,” said Representative Peter Welch, Democrat of Vermont.

Reporting was contributed by Maggie Haberman, Catie Edmondson, Sheryl Gay Stolberg and Michael D. Shear.