“His conduct over the last eight weeks has been injurious to the country and incredibly harmful to the party,” said Chris Christie, the former governor of New Jersey who was the first major Republican to endorse Mr. Trump.

Mr. Christie said Republicans must “separate message from messenger,” because “I don’t think the messenger can recover from yesterday.”…

Standing after midnight in a Capitol Rotunda still littered with the dirt and detritus left behind by the mob that breached the building, Mr. Upton said: “This is his legacy, not the tax cuts, not the judges. Today.”

Senator Lisa Murkowski of Alaska, who Mr. Trump has also demanded be unseated, offered a measure of deadpan when she said Republicans should part ways with their divisive leader. “I think today is a pretty good reason why,” Ms. Murkowski said walking into a Senate chamber surrounded by machine gun-bearing law enforcement officers.