WASHINGTON — On a Saturday afternoon in October 1990, Senator Pete Domenici turned from a conversation on the Senate floor, caught the eye of a clerk by raising his right hand, and voted in favor of a huge and contentious bill to ­reduce federal deficits. Then he put his hand back into his pocket and returned to the conversation.

It was the end of an era, ­although no one knew it then. It was the last time any congressional Republican has voted for higher income taxes.