House Managers Adam Schiff (C) and Jerry Nadler (R) speak to reporters on the fourth day of the Senate impeachment trial on January 24
Donald Trump's lawyers prepared to deliver his first full-throated defense Saturday in the Senate's historic impeachment trial, after Democratic prosecutors spent three days making their case for the US president's removal from office.
Capping 24 total hours of arguments, Democrats told the 100 senators that Trump abused the power of the presidency in pressuring Ukraine to launch investigations that would help him politically, and then sought to block efforts by Congress to investigate.
Democrats said they had met that burden of proof, as lead House impeachment manager Adam Schiff warned that Trump would remain an "imminent threat" to American democracy if he stays in power.
"This is Trump first, not America first," congressman Schiff told the chamber.
"I ask you, I implore you," he added, addressing Republicans who hold the power to allow witnesses to testify, against Trump's wishes.
"Give America a fair trial," Schiff said. "She's worth it."
Trump has signalled he remains in tight control of his party, with many Senate Republicans expressing public support for the president despite a vigorous, comprehensive case outlining his misconduct.
"I don't believe anything they've said so far is impeachable," Senator Rick Scott told reporters.
"I'm looking forward to the White House tomorrow starting to set the record straight, because this has just been partisan."
Trump's team begin their defense at 10:00 am (1500 GMT) Saturday, a timeslot which Trump, a former reality television star, referred to in a tweet as "Death Valley in T.V."
His side's arguments will continue Monday and Tuesday, before the chamber turns to questioning and then votes on whether to hear from witnesses, something Democrats have sought from the start.
Trump's defense will be "much more concise" and "easier to understand" than the prosecution arguments, Republican Senator Mike Braun told Fox News.
Democrats argued that Trump's refusal to allow top officials to testify and to supply subpoenaed documents to the Ukraine investigation supported the second charge against him, obstruction of Congress.
Trump blocked the executive branch from responding to 71 specific requests for documents, including five subpoenas, related to his pressure on Kiev to help his 2020 reelection effort, Democratic impeachment manager Val Demings told senators.
Trump also prevented 12 current and former administration officials, most of them subpoenaed, from testifying to the investigation, she said.
"President Trump's obstruction of the impeachment inquiry was categorical, indiscriminate and historically unprecedented," Demings said.
- 'Absolute power corrupts' -
She said Congress could not afford to allow Trump to reject its powers in such a wholesale manner.
"Executive power without any sort of restraint, without oversight, and without any checks and balances, is absolute power," she told the Senate hearing.
"And we know what has been said about absolute power. Absolute power corrupts, absolutely."
On Twitter, Trump dismissed the entire process.
"The Radical Left, Do Nothing Democrats have gone crazy," he tweeted.
"They know it's a con, but just can't sell it! Public strongly against Impeachment."
Americans appear about evenly split on whether Trump should be impeached and removed. Several polls show a healthy majority want the Senate to subpoena key witnesses for Trump's trial.
- Fight over subpoenas -
Closure of the Democrats' opening arguments paves the way for Trump's team to urge acquittal in only the third ever impeachment trial of a US president.
Trump's clearance is virtually assured: Senate Republicans hold a 53-47 majority, and a vote by 67 senators is required for conviction and removal.
Democrats were hoping however to woo some Republicans to embrace their arguments that the Senate should subpoena four current and former White House officials with direct knowledge of Trump's Ukraine machinations.
There were hints that at least two or three Republicans were considering supporting the subpoenas, though none had committed.
But without four crossovers, analysts were predicting that Senate Majority Leader Mitch McConnell, a key Trump defender, would be able to bring the trial to a vote on the charges by late next week, and see Trump soon exculpated on a party-line vote.
- 'Rebut and refute'-
If Democrats gain support for subpoenas, Republican leaders threatened to demand their own witnesses and call Democratic presidential hopeful Joe Biden and his son Hunter to testify, because their connections to Ukraine had been at the heart of Trump's scheme to tarnish his election rivals.
Trump and McConnell also suggested the president would claim executive privilege to reject the subpoenas, which would lead to court challenges and ensure that the trial could go on for weeks more.
Neither party relishes that thought as the battle ahead of November elections intensifies.
The prosecution showed senators scores of videos, internal documents and extensive witness testimony to lay out their case that Trump abused his powers.
Before a national television audience, Democrats detailed how Trump flagrantly undertook last year to force Kiev to help him tarnish Biden.
Trump defense lawyer Jay Sekulow said they would open their reply by putting on an "affirmative case" that would "rebut and refute" those arguments.