“It’s asking a lot from people on the center-right or in the old Reagan wing of GOP to go full Sanders in November,” said Jerry Taylor, who runs the Niskanen Center, a Washington think tank that has become a hub for the Never Trump community. Taylor does plan to support Sanders in the general election if the senator wins the Democratic nod but described himself, and others like him, as the exception to the rule.

“I would not feel particularly happy about it, but I would swallow hard and pull the lever,” Taylor said.

Should Sanders emerge, Never Trump Republicans say they and independent conservatives itching to oust Trump in the fall are likely to sit on their hands or vote for a hopeless third-party candidate in protest.

That is what Longwell concluded after two years and several focus groups with persuadable voters in the Rust Belt as part of her extensive research into the best strategy for holding Trump to a single term.