• Video report by ITV News Washington Correspondent Robert Moore

US Democratic House prosecutors launched their final arguments on Friday at Donald Trump’s impeachment trial, insisting the president only released congressionally approved military money to Ukraine because he had “got caught” withholding it.

“The scheme was unravelling,” said Representative Jason Crow, a former Army ranger, as the prosecution wrapped up its presentation on the first article of impeachment, abuse of power, before turning to the charge of obstruction of Congress.

As Democrats pressed their case before Republican senators for a third day, the president’s legal team was preparing its defence, expected to start on Saturday.

Mr Trump, eyes on the audience beyond the Senate chamber, bemoaned the schedule in a tweet, saying “looks like my lawyers will be forced to start on Saturday, which is called Death Valley in T.V.”

Representative Jason Crow speaks during the impeachment trial against President Donald Trump Credit: Senate Television via AP

The president is being tried in the Senate after the House impeached him last month, accusing him of abusing his office by asking Ukraine for politically motivated probes of political foe Joe Biden and Mr Biden’s son while withholding military aid from a US ally that was at war with bordering Russia.

The second article of impeachment accuses him of obstructing Congress by refusing to turn over documents or allow officials to testify in the House probe.

Mr Crow said the money for Ukraine was released once Congress intervened.

“It wasn’t lifted for any legitimate reason,” Mr Crow told the senators. “It was only lifted because President Trump had got caught.”

Republicans have defended Mr Trump’s actions as appropriate and are casting the process as a politically motivated effort to weaken him in his reelection campaign.

Republicans hold a 53-47 majority in the Senate, and acquittal is considered likely.

The Senate is heading next week toward a pivotal vote on Democratic demands for testimony from top Trump aides, including acting chief of staff Mick Mulvaney and former national security adviser John Bolton who refused to appear before the House.

It would take four Republican senators to join the Democratic minority to seek witnesses, and so far the numbers appear lacking.

“This needs to end,” said Senator Lindsey Graham, a Trump confidant. He said he does not want to hear from Mr Bolton or the Bidens.

With Chief Justice John Roberts presiding, Democrats argued on Thursday that Mr Trump’s motives were apparent, that he abused power like no other president in history, swept up by a “completely bogus” Ukraine theory pushed by lawyer Rudy Giuliani.

  • The impeachment trial explained

Representative Adam Schiff, the Democratic chairman of the House Intelligence Committee, made an emotional plea late on Thursday for senators to consider what was at stake.

“Let me tell you something. If right doesn’t matter, it doesn’t matter how good the Constitution is,” Mr Schiff told a pin-drop-quiet room.

“If you find him guilty, you must find that he should be removed. Because right matters.”

They argued that Mr Trump’s abuse was for his own personal political benefit ahead of the 2020 election, even as the nation’s top FBI and national security officials were publicly warning off the theory that it was Ukraine, not Russia, that interfered in the 2016 election.

“That’s what Donald Trump wanted investigated or announced — this completely bogus Kremlin-pushed conspiracy theory,” Mr Schiff declared.

The Democrats’ challenge is clear as they try to convince not just fidgety senators but an American public divided over the Republican president in an election year.

A new poll from The Associated Press-NORC Centre for Public Affairs Research showed the public slightly more likely to say the Senate should convict and remove Mr Trump from office than to say it should not, 45% to 40%.

But a sizable percentage, 14%, said they did not know enough to have an opinion.

Adam Schiff, the Democratic chairman of the House Intelligence Committee. Credit: AP

One issue with wide agreement is that Mr Trump should allow top aides to appear as witnesses at the trial.

About seven in 10 respondents said so, including majorities of Republicans and Democrats, according to the poll.

After both sides have concluded their arguments next week, senators will face the question of whether to call witnesses to testify.

But that issue has seemed all but settled. Republicans rejected Democratic efforts to get Trump aides, including Mr Bolton and Mr Mulvaney, to testify in back-to-back votes earlier this week.