Mr. Parnas, who is under federal indictment, has only recently been cleared to hand over the material to Congress, and an official involved in the inquiry indicated more was likely to be made public soon.

Senior Democrats who led the House impeachment inquiry said the new records underscored the need for senators to demand additional evidence at trial. The new documents, they said in a statement, “demonstrate that there is more evidence relevant to the president’s scheme, but they have been concealed by the president himself.”

“There cannot be a full and fair trial in the Senate without the documents that President Trump is refusing to provide to Congress,” they said.

Ms. Pelosi said she would announce the names of her impeachment managers at 10 a.m. Wednesday, and a vote to formally name them and send the articles was scheduled for early afternoon. “The American people deserve the truth, and the Constitution demands a trial,” she said.

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

But after weeks of demanding the charges be brought forward speedily, he said the Senate would put off considering the terms of the trial or the substance of the case for nearly a week, until next Tuesday. That would allow lawmakers time to vote late this week to approve Mr. Trump’s new trade agreement with Canada and Mexico and give senators time to travel home this holiday weekend before the trial requires them to remain at their desks in the Senate chamber six days a week.

The announcements paved the way for a choreographed exchange between the two chambers that will 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.