President Donald Trump’s impeachment trial faces a climactic vote on Friday, when senators are due to decide whether to call witnesses and prolong the historic proceeding or instead bring them to the swift conclusion that Trump wants.

The U.S. Senate will conclude its impeachment trial of U.S. President Donald Trump next week, with a final vote set for Wednesday. The Republican-controlled chamber is all but certain to acquit the president.

Democrats appeared to have fallen short on Thursday in their bid to garner the votes needed to call witnesses in President Donald Trump's impeachment trial, clearing the way for his likely acquittal as early as this weekend.

Republican Senator Lamar Alexander said on Thursday that he would vote against calling witnesses in the impeachment trial of President Donald Trump, dealing a blow to Democrats who had hoped to hear from current and former top Trump aides.

U.S. President Donald Trump campaigned on Thursday in Iowa - the state that kicks off the presidential nominating race next week - basking in the support of his base while the U.S. Senate trial considering his impeachment continued in Washington.

Democratic prosecutors and Republican defenders at President Donald Trump's impeachment trial on Thursday barreled toward a confrontation over new witnesses, something that would deny Trump the swift conclusion of the matter that he seeks.

U.S. Republican Senator Lisa Murkowski suggested she may break with her party and vote in favor of calling additional witnesses, including former national security adviser John Bolton, in the Senate impeachment trial of President Donald Trump.

U.S. Senate Republicans on Thursday tried to shift the focus of President Donald Trump's impeachment trial to the unnamed government official whose whistleblower complaint about Trump's dealings with Ukraine spurred the drive to remove him from office.

U.S. senators on Thursday spent the day posing questions to the Democratic lawmakers prosecuting the impeachment case against President Donald Trump and the lawyers defending him.

A senior Senate Republican said momentum was building on Thursday for a quick end to President Donald Trump's impeachment trial despite a push by Democrats to call witnesses such as former national security adviser John Bolton.