Representative Liz Cheney of Wyoming, the No. 3 House Republican, announced on Tuesday that she would vote to impeach President Trump, saying there had “never been a greater betrayal by a president of the United States” than Mr. Trump’s incitement of a mob that attacked the Capitol last week. In a stinging statement that drove a fissure through her party, Ms. Cheney dismissed fellow Republicans arguing that the impeachment was rushed, premature or unwarranted. Her words were unequivocal and likely to give cover to two dozen or so other House Republicans looking to break ranks and join an effort that...
