Discussions between rival donors are commonplace; many are friends and have worked together on previous campaigns. But conversations accelerated after the debate in Boulder. Rubio bundlers are quietly reaching out to ensure that Bush donors know they would be welcomed into the fold if their candidate falters. Some Bush bundlers, their confidence in the governor irreparably damaged despite a successful fourth debate, have responded with private overtures of support for their second choice.

“This is the joyous candidate, right? Whatever problems Jeb’s campaign may have are a function of Jeb himself as a candidate, and you don’t repair those by tearing down some other guy,” said a prominent Bush bundler, who requested anonymity in order to speak candidly.

“Many of us think very highly of Marco,” the bundler continued. “I’m a huge fan of Marco Rubio — have been since the very, very early days. We were with him and supporting him when he was just a blip in the polls against Charlie Crist. And, he is [the] future of [the] party. So [attacking him] doesn’t seem to be an astute, timely or effective strategy. I’m hearing awful lot of folks saying that.”