U.S. Senate Majority Leader Mitch McConnell (Front) heads to the Senate Chamber before the start of the Senate impeachment trial on Capitol Hill in Washington D.C., the United States, on Jan. 21, 2020. The impeachment trial against U.S. President Donald Trump kicked off Tuesday in the Senate as the chamber debated, and would later vote on, a resolution stipulating rules guiding the process. (Photo by Ting Shen/Xinhua)

The impeachment trial against US President Donald Trump kicked off Tuesday in the Senate as the chamber debated, and would later vote on, a resolution stipulating rules guiding the process.

With Supreme Court Chief Justice John Roberts presiding over the session and the Senate clerk finishing reading the draft resolution proposed by Senate Majority Leader Mitch McConnell, the two opposing sides - House managers as prosecutors and Trump's legal defense team - debated the trial rules.

Speaking on the Senate floor on behalf of the lawyers representing Trump in the trial, White House Counsel Pat Cipollone defended McConnell's draft resolution. "We support this resolution. It is a fair way to proceed with this trial," he said.

In a last-minute change to his original resolution, McConnell extended the duration of the 24-hour time slot granted to each of the two opposing sides in President Donald Trump's impeachment trial for their opening statements from two days to three days. The resolution was firmly opposed by Democrats.

"We believe that once you hear the initial presentations, the only conclusion will be that the president has done absolutely nothing wrong, and that these articles of impeachment do not begin to approach the standard required by the Constitution," said Cipollone.

Trump was impeached in December by the Democratic-controlled House, which passed two articles of impeachment accusing him of abuse of power and obstruction of Congress.

House Intelligence Committee Chairman Adam Schiff, who has led the House impeachment inquiry and who now heads the team of House managers, denounced McConnell's proposal, saying "the resolution should allow the House managers to call their witnesses, and then the President should be allowed to do the same and any rebuttal witnesses."

"Why should this trial be different than any other trial? The short answer is it shouldn't. But leader McConnell's resolution would turn the trial process on its head," Schiff, a California Democrat, said, adding that "the president places himself beyond accountability, above the law."