Republican senators began to justify their coming votes to acquit Donald Trump on two impeachment articles – complete with some creative political contortions – as the Senate's impeachment trial endgame remained murky.

Senators have yet to settle on just how the trial will wrap up, but final votes that would clear the president on both impeachment articles could still occur late Friday night or early Saturday morning. Members and both parties' leaders are mulling a plan under which the chamber would adjourn as an impeachment court until Monday with final votes on Wednesday after two days of closing arguments and further deliberation.

One congressional source said it was "unlikely" the trial would end on Friday night or early on Saturday. Pushing the end of the trial to Wednesday would mean Mr Trump would deliver his State of the Union address the night before, giving him a chance to mock the very House Democrats who impeached him just hours before the Senate clears him on both charges.

As some moderate GOP senator-jurists explained their decisions to, as expected later on Friday, help their Republican colleagues kill a motion that could allow witnesses to be called in Mr Trump's trial, others took the next step. They began explaining why they intend to clear the president, just the third to ever be impeached, on charges of abusing his presidential powers and obstructing House Democrats' investigation of his actions toward Ukraine related to dinging his top domestic political foes.

"Voting to find the president guilty would not just be a condemnation of his action. If I vote guilty, I will be voting to remove a President from office for the first time in the 243-year history of our Republic," Senator Marco Rubio, once a rising star in his party with presidential aspirations, said in a statement.

"That is why six weeks ago I announced that, for me, the question would not just be whether the president's actions were wrong, but ultimately whether what he did was removable. The two are not the same," said the man Mr Trump, as a candidate, once mocked as "Little Marco".

"Just because actions meet a standard of impeachment does not mean it is in the best interest of the country to remove a president from office" he added.

Mr Rubio became the latest Senate Republican – Tennessee's retiring Lamar Alexander did so late on Thursday – to state publicly they have concluded Mr Trump did the things House Democrats alleged in their articles and prosecution case. "I assumed what is alleged is true," he said, justifying his coming acquittal vote by pointing to America's era of tribal politics.

"I will not vote to remove the president because doing so would inflict extraordinary and potentially irreparable damage to our already divided nation," Mr Rubio said.

Prior to Mr Alexander's announcement all eyes were on a handful of Republican moderates in the unresolved debate about allowing witnesses. One was Alaska's Lisa Murkowski. She put an end to questions about her intentions with an equally nuanced statement on Friday that also blamed partisanship.

"Given the partisan nature of this impeachment from the very beginning and throughout, I have come to the conclusion that there will be no fair trial in the Senate. I don't believe the continuation of this process will change anything," Ms Murkowski said.

"It is sad for me to admit that, as an institution, the Congress has failed," she added, blaming the other 534 members of the House and Senate – but not herself.

Republicans' signalling their intentions overshadowed the proceedings on the floor, which featured both sides regurgitating their diverging views of seeking new witnesses and testimony.

House Intelligence Committee Chairman Adam Schiff began his side's portion of the talk-a-thon by noting a New York Times article published on Friday contended that White House Counsel Pat Cipollone was in the room when Mr Trump told then-national security adviser John Bolton, whom he eventually fired, that he should tell Ukraine's president the military aid was contingent on announcing a probe of the Bidens.

Mr Schiff criticised Mr Cipollone for contending the House Democratic managers had withheld information or cherry-picked details to strengthen their prosecution, alleging Mr Cipollone had done the same.

"The facts will come out," Mr Schiff told senators. "And the question before you today is will they come out before you have time to make an informed decision."