WASHINGTON — Ahead of a House vote Tuesday calling for Vice President Mike Pence to invoke the 25th Amendment to remove President Donald Trump from office, a growing number of Republicans are backing impeaching the president with roughly one week left in his term.

Rep. Liz Cheney, R-Wyo., a member of GOP leadership, announced Tuesday night she will vote to impeach the president.

"There has never been a greater betrayal by a President of the United States of his office and his oath to the Constitution," Cheney said in a statement.

Cheney, a conservative member of the party and the daughter of former Vice President Dick Cheney, could lead other Republicans weighing voting for impeachment to break from the president.

"The President of the United States summoned this mob, assembled the mob, and lit the flame of this attack. Everything that followed was his doing. None of this would have happened without the President. The President could have immediately and forcefully intervened to stop the violence. He did not," she added.

The House is planning to vote Wednesday on an article of impeachment that would charge Trump with "incitement of insurrection." No U.S. president has ever been impeached twice.

The impeachment measure is expected to quickly follow Tuesday night's vote by the House urging Pence to invoke the 25th Amendment.