In a modern-day variation on "better red than dead," Joe Scarborough claims that Haley Barbour and many Republican leaders would "much rather" have Hillary be president than to let Trump win and represent the GOP.
If it looks like Trump will win the nomination, which Scarborough sees as very plausible, he envisions Mitt Romney or Michael Bloomberg jumping into the race as a third-candidate. Not really with the goal of winning, but rather to "take a bullet," splitting the vote and denying Trump the White House.