Impeachment trial to begin with rules fight

The Senate trial on the impeachment charges against US President Donald Trump is expected to begin on Tuesday, but the president and his opponents took to Twitter and television on Monday to make their own arguments.

"They didn't want John Bolton and others in the House," Trump tweeted. "They were in too much of a rush. Now they want them all in the Senate. Not supposed to be that way!"

Bolton is Trump's former national security adviser, one of a handful of possible witnesses whom some Senate Democrats want to call during the trial.

"Cryin' Chuck Schumer is now asking for 'fairness', when he and the Democrat House members worked together to make sure I got ZERO fairness in the House. So, what else is new?" Trump tweeted.

Senator Chuck Schumer, leader of the Senate Democrats, tweeted on Monday that "Senator McConnell is trying to stop witnesses and documents from coming to light. Democrats will force a vote on witnesses and documents", in reference to the Republican Senate majority leader.

There are 45 Democratic senators and two independents, who Schumer expects would vote with the Democrats.

If four of the 53 Senate Republicans left their party ranks and joined the other 47 senators, that would provide the simple majority needed for a vote on whether witnesses should be heard at the trial.

Separately, Senate Republican leader Mitch McConnell put forward rules on Monday that could lead to a quick impeachment trial for Trump, with no guarantee that witnesses or new evidence would be allowed.

Under the resolution, which could face a vote as early as Tuesday, lawyers for Trump could move early in the proceedings to ask senators to dismiss all charges, a senior Republican leadership aide said.

The resolution McConnell unveiled would give House Democratic prosecutors and Trump lawyers a total of 48 hours, evenly split, to present their arguments over a maximum of four days.

Also on Monday, Trump's legal team rejected the House of Representatives' impeachment articles and called for their immediate dismissal by the Senate in a memo offering a legal and political case against his removal.

The 116-page Trial Memorandum sought to undercut charges that Trump abused his power and obstructed Congress. The document was Trump's first formal, comprehensive defense against impeachment.

Trump is charged with abusing the powers of his office by asking Ukraine to investigate a 2020 Democratic political rival, former US vice-president Joe Biden, and obstructing a congressional inquiry into his own conduct.

Military assistance

Democrats say Trump abused his power by withholding congressionally approved US military assistance to Ukraine as part of a pressure campaign on the country, and obstructed Congress by refusing to hand over documents and by barring administration officials from testifying when they were subpoenaed by House investigators.

Trump's defense argued neither charge constituted a crime nor an impeachable offense, that he was within his rights as president to make decisions about foreign policy and what information to give Congress, and that the House pursued a flawed and one-sided process before impeaching him on Dec 18.

"House Democrats settled on two flimsy Articles of Impeachment that allege no crime or violation of law whatsoever－much less 'high crimes and misdemeanors', as required by the Constitution," it said. "They do not remotely approach the constitutional threshold for removing a president from office."

The memo's executive summary asserted that the House Democrats' "novel theory of 'abuse of power'" was not an impeachable offense and supplanted the constitutional standard of "Treason, Bribery, or other high Crimes and Misdemeanors".

It rejected the obstruction of Congress charge as "frivolous and dangerous", saying Trump exercised his legal rights by resisting congressional subpoenas.

It also accused the House Democrats of conducting a rigged process, and that they succeeded in proving only that Trump had done nothing wrong. The memo argued, as the White House has repeatedly, that this was an effort to overturn Trump's 2016 election victory and to prevent his reelection in November.

"They want to use impeachment to interfere in the 2020 election. It is no accident that the Senate is being asked to consider a presidential impeachment during an election year," the memo said.

"Put simply, Democrats have no response to the president's record of achievement in restoring prosperity to the American economy, rebuilding America's military, and confronting America's adversaries abroad," it added.

In their own filing with the US Senate on Monday, the House impeachment managers who will make the Democrats case for Trump's removal to the Senate said he had "jeopardized our national security and our democratic self-governance".

But Trump's team said he was within his constitutional authority to press Ukrainian President Volodymyr Zelensky last year to investigate Biden as part of what Trump said was an anti-corruption drive.

Reuters contributed to this story.