Democratic prosecutors and Republican defenders in President Donald Trump's impeachment trial traded barbs in a second day of questioning by U.S. senators on Thursday, with Democrats stressing the importance of calling witnesses such as former national security adviser John Bolton.

The No. 3 Republican in the U.S. Senate said on Thursday Republicans were prepared to stay through the "completion" of President Donald Trump's impeachment trial whether late on Friday or on Saturday.

President Donald Trump's impeachment trial resumed on Thursday for a second day of questioning by U.S. senators before they address the explosive issue of whether to call witnesses such as former national security adviser John Bolton.

The head of the U.S. House Judiciary panel said it might be a good idea for the House of Representatives to subpoena President Donald Trump's former national security adviser John Bolton if the Senate does not call him as an impeachment trial witness, CNN reported.

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 U.S. Senate is expected to wrap up the initial phase of President Donald Trump's impeachment trial on Thursday before turning to the explosive question of whether to call witnesses such as former national security adviser John Bolton.

The U.S. Senate is expected to wrap up the initial phase of President Donald Trump's impeachment trial before turning on Friday to the explosive question of whether to call witnesses such as former national security adviser John Bolton.

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 U.S. Senate is expected to wrap up the initial phase of President Donald Trump's impeachment trial before turning on Friday to the explosive question of whether to call witnesses such as former national security adviser John Bolton.

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.