Donald Trump's impeachment trial opened on Tuesday with a debate about whether the US Constitution allows a former president to face trial after he has left office.
A similar effort led by Republican Senator Rand Paul last month led to 45 out of 50 fellow Senate Republicans voting the trial was unconstitutional.
On Tuesday, one additional Republican senator voted the trial was allowable under the Constitution. Here's a look at the six Republican senators who backed that argument:
The Nebraska senator handily won reelection in 2020 and is considered a potential contender for the 2024 Republican presidential nomination. He publicly denounced here Trump's false claims of widespread electoral fraud and said there was no basis to object to Democrat Joe Biden's November 3 victory.
The Louisiana senator changed his vote from his earlier one, backing arguments on Tuesday that the trial was constitutional. Cassidy told reporters after the House impeachment managers presented their side that they had "a very good opening."
Murkowski of Alaska became the first US senator in 50 years to win an election with a write-in campaign in 2010 after losing in the Republican primary. She called for Trump to resign after his followers rioted at the US Capitol on January 6 to disrupt the formal certification of the election by Congress.
Romney, a Utah senator and the 2012 Republican presidential candidate, has been a vocal critic of Trump. In 2020, Romney was the only Republican senator to vote for conviction during Trump's first impeachment trial.
The Pennsylvania senator announced in October 2020 he would not be seeking re-election. He said in television interviews Trump committed "impeachable offenses" and called on him to resign after the January 6 attack.
The Maine centrist was the only Republican senator re-elected in 2020 in a state also won by Biden. She said Trump had incited the January 6 riot.