Republican senators to watch in battle over Trump impeachment trial witnesses

U.S. Senator Lindsey Graham (R-SC) speaks to reporters as he exits the Trump impeachment trial in Washington, U.S., January 29, 2020. REUTERS/Brendan McDermid

(Reuters) - The U.S. Senate is holding an impeachment trial on charges by the House of Representatives that President Donald Trump abused his powers and obstructed a congressional inquiry into whether he put pressure on Ukraine to investigate Democratic presidential contender Joe Biden.

The Republican-controlled Senate is expected to vote as soon as Friday over whether witnesses and new documents should be part of the trial.