“If we try to play our own version of identity politics and try to fuel ourselves based on darker emotions, that’s not productive,” Mr. Ryan said in a wide-ranging interview on Friday. “I don’t think it will be successful, and I don’t think it is the right thing to do. I believe in an agenda that’s inspirational, that’s inclusive, that’s optimistic.”

Mr. Ryan, the Republican nominee for vice president in 2012, added his powerful voice to a growing line of leaders of his party’s establishment sounding an alarm about the tenor of the race just weeks before the first votes are cast in the nominating contests.

“This isn’t about Trump,” Mr. Ryan said. “This is about do we run on substance or do we run on personality? If we run on personality, we lose those elections.”…

“I come from the pro-growth wing of the Republican movement,” he continued. “I believe in an aspirational type of conservative that should prevail for lots of reasons, for moral reasons and because I think it’s more successful. This is another chapter in that long evolving story.”