Washington, Jan 21 (AP) Senate Majority Leader Mitch McConnell abruptly changed his proposed rules for President Donald Trump's impeachment trial, backing off the condensed two-day schedule to add a third for opening arguments after protests from senators, including Republicans.

The trial quickly burst into a partisan fight at the Capitol as the president's lawyers opened arguments Tuesday in support of McConnell's plan.

Democrats objected loudly to McConnell's initially proposed rules, and some Republicans made their concerns known in private.

Without comment, the Republican leader quietly submitted an amended proposal for the record, after meeting behind closed doors with senators as the trial opened. He added the extra day and allowed House evidence to be included in the record.

"It's time to start with this trial," said White House Counsel Pat Cipollone, the president's lead lawyer as the proceedings opened in public.

"It's a fair process," he said. "There is absolutely no case."

Chief Justice John Roberts gaveled open the session, senators having taken an oath last week to do "impartial justice" as jurors.

Senators were stunned by McConnell's shift, and aides offered no immediate answers/ But a spokeswoman for Republican Sen. Susan Collins said that she and others had raised concerns. The Maine senator sees the changes as significant improvements, said spokeswoman Annie Clark.

Democrats had warned that the rules package from Trump's ally, the Senate GOP leader, could force midnight sessions that would keep most Americans in the dark and create a sham proceeding.

"This is not a process for a fair trial, this is the process for a rigged trial" Rep. Adam Schiff, D-Ca., the chairman of the House Intelligence Committee leading the prosecution, told reporters. He called it a "cover-up".

McConnell opened the chamber promising a "fair, even handed" process — and warned that the Senate would stay in session until his proposed rules package was adopted.

"The president's lawyers will finally receive a level playing field," the Kentucky Republican said, contrasting it with the House impeachment inquiry.

The first test was coming as senators prepared to begin debate and vote on McConnell's proposed rules.

The rare impeachment trial, unfolding in an election year, is testing whether Trump's actions toward Ukraine warrant removal at the same time that voters are forming their own verdict his White House.

The Democrats say the prospect of middle-of-the-night proceedings, without allowing new witnesses or even the voluminous House records of the trial, will leave the public without crucial information about Trump's political pressure campaign on Ukraine and the White House's obstruction of the House impeachment probe.

"The McConnell rules seem to be designed by President Trump for President Trump," said the Senate Democratic leader, Chuck Schumer.

He vowed to call for a series of votes to amend the rules and demand testimony and documents, but it seemed unlikely Republicans would break from the party to join Democrats.

"This is a historic moment," Schumer said. "The eyes of America are watching. Republican senators must rise to the occasion."

If the senators agree to McConnell's proposal for speedy trial and acquittal, Schiff said, "It will not prove the president innocent, it will only prove the Senate guilty of working with the president to obstruct the truth from coming out."

Rep. Jerry Nadler, the Judiciary Committee Chairman also leading the House team, said: "There's no trial in this country where you wouldn't admit relative witnesses."

McConnell had promised to set rules similar to the last impeachment trial, of President Bill Clinton in 1999, but his resolution diverged in key ways.

GOP Senator Mitt Romney of Utah, whose votes are being closely watched, said he was satisfied with the proposal, even as he hopes to hear from former national security adviser John Bolton who had a front-row seat to Trump's actions.

The first several days of the trial are expected to be tangled in procedural motions playing out on the Senate floor and behind closed doors. Senators must refrain from speaking during the trial proceedings.

Like Trump, House Speaker Nancy Pelosi will also be away for the proceedings, leading a bipartisan congressional delegation to Poland and Israel to commemorate the 75 years since the liberation of Auschwitz at the end of World War II.

She issued a statement on Tuesday denouncing McConnell's proposed ground rules as a "sham" because of the compressed schedule and lack of guarantee that witnesses will be called or that evidence gathered by the House would be admitted in the Senate trial. (AP)

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