The most consequential day in Donald Trump’s impeachment trial has begun in the US Senate, with Republican leaders likely to muster enough votes to block witnesses and rapidly move to acquit the president.

The decision by Senator Lamar Alexander of Tennessee, a Republican who had been considered a potential supporter of testimony, to vote against new evidence largely dashed Democrats hopes of prevailing. His announcement is a victory for

Trump’s legal team and, especially, Senate Majority Leader Mitch McConnell, who had been steering the trial to a quick conclusion after two weeks of debate and questioning.

The Senate began on Friday with House prosecutors and Trump’s defence each delivering two hours of arguments.