Day two of President Donald Trump’s impeachment trial began with a shock, when Senate Majority Leader Mitch McConnell abruptly changed his proposed rules for the trial.

Watch the trial live here.

Backing off from his condensed two-day schedule, McConnell allowed a third day for opening arguments after protests from senators, including Republicans.

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.

Also on Tuesday, Democrats unsuccessfully tried to add provisions that would have required senators to subpoena White House and Office of Management and Budget documents they claimed were related to the case. Voting along party lines, senators tabled each amendment.

“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 open the session at 1 p.m., with House impeachment managers and Trump’s legal team taking the Senate well for opening statements and speeches that lasted well past 7 p.m.

VIDEO: Impeachment trial for President Trump begins Tuesday

The trial’s first several days are almost certain to be tangled in procedural motions playing out on the Senate floor or behind closed doors, as senators must refrain from speaking during the trial proceedings.

»How to contact your Georgia congress members on impeachment

“All of this is a dangerous perversion of the Constitution that the Senate should swiftly and roundly condemn,” the president’s lawyers wrote in their first full filing Monday. “The articles should be rejected and the president should immediately be acquitted.”

The U.S. House formally sent President Donald Trump's impeachment articles to the Senate on Jan. 15, 2020. House Speaker Nancy Pelosi first announced seven impeachment managers. The House then voted, along party lines, to transmit the impeachment articles across the aisle. Pelosi signed the House's order, then gave fellow Democrats souvenir pens for the occasion. The impeachment managers, along with Capitol clerical personnel, then marched over to the Senate. Trump has been charged with abuse of power

Democrats — as the House prosecutors practiced opening arguments well into the night on the Senate floor — vowed to object to a speedy trial as they pressed for fresh witnesses and documents.

Senate Democratic leader Chuck Schumer warned of a “cover-up” with McConnell’s plan that could lead to back-to-back 12-hour days.

“It’s clear Sen. McConnell is hell-bent on making it much more difficult to get witnesses and documents and intent on rushing the trial through,” Schumer said. He called the proposed rules a “national disgrace.”

Late Monday, Trump named eight House Republicans, including U.S. Rep. Doug Collins from Georgia's 9th district, to a special team tasked with rallying support beyond the Senate chamber in the court of public opinion.

U.S. Rep. Doug Collins is the ranking Republican on the House Judiciary Committee. Elected to Congress in 2012, Collins represents north Georgia's 9th district. He has become one of President Trump's most ardent supporters ... and one of the most vocal critics of Democrat-led impeachment efforts. The president asked Georgia Gov. Brian Kemp to appoint Collins to replace the retiring Sen. Johnny Isakson. Kemp is appointing business executive Kelly Loeffler instead. Regardless, Collins may run for the Senate

House Democrats impeached the Republican president last month on two charges: abuse of power by withholding U.S. military aid to Ukraine as he pressed the country to investigate Democratic rival Joe Biden, and obstruction of Congress by refusing to cooperate with their investigation.

»MORE: 8 GOP House members named to Trump defense team

But despite Democrats' professed sense of urgency in pushing through the articles along party lines, House Speaker Nancy Pelosi delayed sending the charges over to the Senate for weeks. Pelosi was demanding information from the Senate on how it plans to conduct Trump's trial and hoped to give Schumer more leverage in talks with McConnell.

Trump is only the third sitting president in American history to be impeached, joining Andrew Johnson and Clinton.

John Roberts serves as the 17th Chief Justice of the United States. He was born in Buffalo, N.Y., and grew up in the Midwest. He completed his undergraduate degree at Harvard and then attended Harvard Law School, graduating with a law degree in 1979. Roberts worked as a clerk during his early legal career, then went into private practice, arguing 39 cases before the Supreme Court. Roberts was appointed to the U.S. Court of Appeals in 2003. President George W. Bush nominated Roberts to the Supreme Court af

The two articles of impeachment by House Democrats − abuse of power and obstruction of Congress − point to Trump pressuring Ukraine to investigate Biden while withholding as leverage military aid the country relies to counter Russia as well as his efforts to block the House investigation.

McConnell has promised to set rules similar to Clinton's trial, but his resolution diverged in key ways, which may leave some senators from both parties uneasy.

President Bill Clinton was impeached on perjury and obstruction of Congress charges on Dec. 19, 1998. He was acquitted by the Senate on Feb. 12, 1999. Fourteen senators from that trial still remain in office. Here's how they voted. Susan Collins, R-Maine. Not guilty on both counts Michael D. Crapo, R-Idaho. Guilty on both counts Richard Durbin, D-Illinois. Not guilty on both counts Mike Enzi, R-Wyoming. Guilty on both counts Dianne Feinstein, D-California. Not guilty on both counts Charles Grassley, R-Iow

After the four days of opening arguments, senators will be allowed up to 16 hours for questions to the prosecution and defense, followed by four hours of debate. Only then will there be votes on whether or not to call other witnesses.

At the end of deliberations, the Senate would then vote on each impeachment article.

The Constitution requires a two-thirds majority in the Senate to convict in an impeachment trial, thus making Trump’s actual removal from office highly unlikely in the GOP-controlled Senate.

The Associated Press contributed to this report.