The third Senate impeachment trial of a US president in history convened on Thursday with the reading of the two impeachment articles charging President Donald Trump with abuse of power and obstruction of Congress.

The seven House impeachment managers who will prosecute the case against the President marched the articles from the House to the Senate on Thursday, beginning the ceremonial functions of the impeachment trial in which senators will decide whether Trump should be removed from office.

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House Intelligence Chairman Adam Schiff, a California Democrat and the lead impeachment manager, read the articles in the chamber shortly after noon ET.

The outcome of the trial is all but determined, as the two-thirds vote required to remove the President would need 20 Republican senators to break ranks. But that doesn’t mean the trial itself won’t have twists and turns — and potentially some surprises — as Senate Majority Leader Mitch McConnell navigates the demands of his Senate conference, pressures from Democrats and the whims of Trump and his Twitter account.

Already this week, indicted Rudy Giuliani associate Lev Parnas has upended the impeachment conversation by providing the House Intelligence Committee with a trove of evidence about his work with Giuliani’s efforts to oust former US Ambassador to Ukraine Marie Yovanovitch last spring and then pressure Ukraine to investigate former Vice President Joe Biden and his son Hunter Biden.

And the Government Accountability Office, a nonpartisan congressional watchdog, said Thursday that the Trump administration violated the law when it withheld Ukraine security aid that Congress has appropriated.

That evidence is likely to be incorporated into the House Democratic case against the President, which they will begin presenting next Tuesday when the substance of the trial gets underway. Democrats charge that Trump withheld the security aid and a White House meeting from Ukraine while pushing for an investigation into the Bidens.

On Thursday, the Senate dispensed with the ceremonial functions of the impeachment trial.

The House impeachment managers began the proceedings by reading aloud the two articles of impeachment on the floor of the Senate. It was the second time they took the articles from the House to the Senate — the managers took the same walk on Wednesday to notify the Senate of the articles, in an odd bit of ceremonial flair that comes with an impeachment trial of the President.

Later on Thursday, Chief Justice John Roberts will arrive to be sworn in to preside over the trial, and Roberts will swear in the senators for the trial.

Next Tuesday, the Senate is expected to vote on a resolution setting the rules of the trial, and then arguments will get underway.

The trial is only beginning this week after House Speaker Nancy Pelosi withheld the formal sending of the articles for four weeks while Democrats pushed for Republicans to agree to calling witnesses and obtaining new documents for the trial.

Pelosi said at her weekly press conference Thursday that Senate Republicans are “afraid of the truth,” when asked what her response is to Senate Republicans who say they shouldn’t have to consider new evidence like the Parnas material because it wasn’t included in the House investigation.

“They don’t want to see documents, they don’t want to hear from eyewitnesses,” Pelosi said. “They want to ignore anything new that comes up.”

McConnell has rejected the Democratic demands, saying the question of witnesses should be taken up after the House and the President’s legal team make their opening arguments. Republicans are expected to pass the rules to put off the question of witnesses without Democratic votes.

McConnell on Thursday criticized Pelosi on the Senate floor for distributing souvenir pens while signing the impeachment articles on Wednesday.

“Nothing says seriousness and sobriety like handing out souvenirs, as though this were a happy bill-signing instead of the gravest process in our Constitution,” he said.