In boost for Trump, key Republican senator opposes calling witnesses

A key Republican senator said late on Thursday that he would oppose calling new witnesses at Donald Trump's impeachment trial, paving the way for the possible acquittal of the president by the Senate as early as Friday.

Senator Lamar Alexander of Tennessee said he would vote "no" when the question of calling further witnesses at the trial is considered on Friday.

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Four Republican votes were needed to introduce new witnesses into the proceedings, and Alexander had been considered one of a handful of Republican senators who might support the motion.

Republican Senator Susan Collins of Maine said she would support the call for witnesses, and Utah Senator Mitt Romney has said he was "very likely" to do so.

Another wavering Republican - Lisa Murkowski of Alaska - has said she will announce her decision on Friday morning.

Republicans hold a 53 to 47 seat edge in the Senate, and four Republicans needed to side with the Democrats for new witnesses to be introduced.

If the motion for new witnesses is rejected, Republican Senate Majority Leader Mitch McConnell could conceivably call for a vote to convict or acquit the president as soon as Friday.

Democrats are particularly eager to hear from former national security advisor John Bolton, who reportedly claims in an upcoming book that Trump personally told him that military assistance to Ukraine was tied to Kiev investigating his Democratic rival Joe Biden.

The charge is at the heart of the December 18 impeachment of the 45th US president for abuse of power and obstruction of Congress by the Democratic-majority House of Representatives.