New proof within the Ukraine strain marketing campaign looms over the trial.

Even because the trial was about to start, lawmakers on each side of the Capitol have been once more wading on Thursday by a trove of newly launched textual content messages, voice mail messages, calendar entries and different information associated to a marketing campaign to strain Ukraine to analyze Mr. Trump’s political rivals.

The proof, handed over by Lev Parnas, provides important new element to the general public report about how the strain marketing campaign undergirding the House impeachment charges performed out and who knew about it. On Wednesday, Mr. Parnas also told The New York Times that he believed Mr. Trump knew that he and Rudolph W. Giuliani, the president’s private lawyer, have been working to dig up dust on his political rivals.

The Home managers may attempt to weaponize items of the fabric as soon as the trial begins, however for now, they hoped the gusher of data would improve strain on Senate Republicans to conform to name witnesses and accumulate new proof through the trial.

Historical past might be made swiftly on Thursday, because the Senate initiates solely the third presidential impeachment trial in American historical past in three hours or much less. The occasions start at midday, and senators could also be on airplanes out of city earlier than enterprise hours are over.

Here’s a run-down of the day’s proceedings, based mostly on steering from Senate officers:

• Earlier than the impeachment trial will get underway, the Senate has some large unfinished enterprise to wrap up. Round 11 a.m. Jap, senators are anticipated to vote to approve Mr. Trump’s long-sought trade agreement with Canada and Mexico.

• At midday, the newly appointed Home managers will assemble on their facet of the Capitol and course of for a second consecutive day to the Senate chamber. This time, they’ll enter with the intention of exhibiting their articles and being launched to senators. This entails studying the articles out loud, in full, as all 100 senators sit quietly at their desks listening.

• The Senate plans to recess every time the Home managers are finished with their presentation. Each events will retreat to their traditional luncheons to debate technique for the approaching trial.

• Chief Justice John G. Roberts Jr. might be escorted into the Senate chamber round 2 p.m. to preside over the trial. Senator Charles E. Grassley of Iowa, the Senate president professional tempore, will swear the chief justice in. His first activity is to manage an oath to all senators, who should swear to do “neutral justice.” Senators will reply orally, however they have to every signal an oath e book to sit down in trial.

• Sooner or later thereafter, the Senate will situation a summons to Mr. Trump informing him of its trial and demanding he reply to the costs, which is able to most certainly be delivered in writing. They will even assign written trial briefs to the Home managers and the president’s authorized groups to be submitted subsequent week.

• With that, the Senate will recess the trial till Tuesday, Jan. 21, to present lawmakers one final lengthy weekend break.