Sen. Mitt Romney, R-Utah, said on Sunday that former President Donald Trump’s Senate impeachment trial is constitutional and that Trump’s alleged involvement in the U.S. Capitol riot is an impeachable offense.

Romney’s comments come after several Senate Republicans have voiced support for a disputed legal argument that holding a Senate trial after a president has left office is unconstitutional.

“It’s pretty clear that the effort is constitutional,” Romney said during an interview on CNN. “I believe that what is being alleged and what we saw, which is incitement to insurrection, is an impeachable offense. If not, what is?”

Trump became the first U.S. president impeached by the House twice after the chamber charged him with high crimes and misdemeanors for inciting an insurrection at the U.S. Capitol on Jan. 6 that left five people dead, including a Capitol Police officer.

A week after the insurrection, 10 Republicans joined all 222 Democrats in voting to charge Trump. The Senate impeachment trial is set to start the week of Feb. 8.

The process will begin Monday when the House files its impeachment article to the Senate. Senators will get sworn in as jurors on Tuesday.

The Senate will need 67 votes to convict Trump. If all Democrats support a conviction, they would need 17 Republicans to join them. If the Senate convicts Trump, he could be barred from becoming president again in 2025.