Open this photo in gallery Senate Minority Leader Chuck Schumer talks to reporters during a break in the Senate impeachment trial of U.S. President Donald Trump at the Capitol in Washington on Jan. 21, 2020. ERIN SCHAFF/The New York Times News Service

Senate Republicans have blocked Democratic attempts to call witnesses and gather more evidence in U.S. President Donald Trump’s impeachment trial as the two sides clashed over the proceeding’s rules on its acrimonious first day.

In a 13-hour session that ended shortly before 2 a.m. Wednesday, the Republican majority stopped 11 Democratic motions to force the White House, Pentagon and State Department to turn over documents related to Mr. Trump’s campaign to press Ukraine into tarnishing presidential rival Joe Biden. They also voted against compelling testimony from four White House officials, including chief of staff Mick Mulvaney and former national security adviser John Bolton.

The Republicans approved rules meant to ensure a swift trial that could be over within two weeks.

Story continues below advertisement

“That’s not a fair trial – that’s a mockery of a trial,” Adam Schiff, the House Democrat leading the prosecution of Mr. Trump, told the Senate. “It is the President’s belief that … he can do anything he wants, no matter how corrupt, outfitted in gaudy legal clothing.”

Mr. Trump’s lawyers called for the Senate to move the trial along as quickly as possible in order to get it over with before the President ramps up his re-election campaign.

“It’s well past time we start this so we can end this ridiculous charade and go have an election,” White House counsel Pat Cipollone said.

The Democratic-controlled House of Representatives impeached Mr. Trump on charges of abuse of office and obstruction of Congress last month. He is accused of withholding nearly US$400-million in American military aid to Ukraine to press Kyiv into helping him take down Mr. Biden, and then stonewalling Congress’s efforts to investigate.

It would take two-thirds of senators to convict Mr. Trump and remove him from office.

Under the trial’s rules, proposed by Republican Majority Leader Mitch McConnell and ultimately adopted on a 53 to 47 party-line vote, each side will have 24 hours over three days apiece to make their arguments. This will be followed by 16 hours of questions from senators, submitted through Chief Justice John Roberts, who is presiding over the proceedings.

Only after this will senators decide whether to subpoena documents or call witnesses.

Story continues below advertisement

But Democrats argued documents and witnesses must be called at the start of the trial so that both sides have access to all the evidence before they make their cases. Pushing this decision to the end of the trial, when such evidence would be less useful, makes it more likely senators would opt not to seek additional evidence at all, the Democrats contended.

Democratic Minority Leader Chuck Schumer moved his motions for documents and witnesses as amendments to Mr. McConnell’s rules. The Republicans voted down every one of them.

The marathon debate was a test of wills for both parties: Mr. Schumer refused Mr. McConnell’s request to bundle all of the amendments into a single vote, insisting on a full debate for each measure to allow Democrats to present some of their evidence against the President. Mr. Schumer in turn rebuffed Mr. McConnell’s suggestion to adjourn to another day, preferring instead to move the proceedings along as quickly as possible.

Zoe Lofgren, a Democratic congresswoman on the prosecution team, pointed to historic precedent. Both previous presidential impeachment trials – Andrew Johnson’s in 1868 and Bill Clinton’s in 1999 – heard from witnesses and reviewed documents.

“Not a single [previous] president has categorically refused to co-operate with an impeachment investigation,” she said.

Mr. Trump refused to co-operate with the House impeachment inquiry, ordering other government officials to also ignore requests for documents or testimony. In addition to Mr. Mulvaney and Mr. Bolton, Democrats want to call as witnesses Mr. Mulvaney’s adviser Robert Blair and budget official Michael Duffey. Mr. Mulvaney, Mr. Blair and Mr. Duffey were involved in the White House freeze on Ukrainian military aid. Mr. Bolton is said to have been angry about the aid being withheld.

Story continues below advertisement

The President's lawyers repeatedly argued Tuesday and Wednesday that House Democrats should have taken administration officials to court if the Democrats wanted this testimony. The Democrats countered that such a process would take years, effectively allowing Mr. Trump to stall impeachment proceedings.

As the debate wore on, nerves frayed and the two sides took increasingly pointed shots at each other, prompting Mr. Roberts to chide them both.

“I think it is appropriate at this point for me to admonish both the House managers and president’s counsel in equal terms to remember that they are addressing the world’s greatest deliberative body,” he said. “Those addressing the Senate should remember where they are.”

Mr. McConnell’s rules were less stringent than he had initially proposed Monday.

His original plan would have compressed each 24-hour period into two days, making for four straight 12-hour sittings that likely would have lasted until after midnight. He also would not have automatically entered into evidence the information already gathered on the case by the House impeachment inquiry.

Mr. McConnell backed down on both points after facing opposition from his own caucus.

Story continues below advertisement

And at least one Republican senator said she was “likely” to vote for witness testimony later in the trial. The Democrats would need four Republicans to vote with them to make this happen.

“It is likely that I would support a motion to subpoena witnesses,” Susan Collins, a Republican from liberal-leaning Maine, said in a statement. Ms. Collins voted with the Democrats on one amendment early Wednesday that would have allowed more time for each side to respond to procedural motions; on the other 10 amendments, she stuck with Mr. McConnell.

The President’s lawyers on Tuesday presented a preview of the arguments they will make once the substantive part of the trial begins in earnest, contending that what Mr. Trump did was not illegal.

Jay Sekulow, one of his lawyers, referred to the charges as “a non-crime allegation of abuse of power and obstruction of Congress.”

The U.S. Constitution does not spell out what offences a president can or cannot be impeached for, referring to “high crimes and misdemeanors,” leaving Congress to decide what exactly those are.

Mr. Trump, for his part, expressed confidence as he attended the World Economic Forum thousands of kilometres away in Davos, Switzerland.

Story continues below advertisement

“That whole thing is a total hoax,” he said. “I’m sure it’s going to work out fine.”

The trial resumes at 1 p.m. on Wednesday. The two sides will first argue any further procedural motions before Democrats begin presenting their case against the President.