I think we can declare his campaign over.

Rubio 57 (+1 vs. last poll, 3/18)
Crist 28 (-6)
Und 12 (+4)

Crist held a 14 point lead in an October Rasmussen poll; the two were tied in mid-December. It’s hard to imagine another turnaround happening before the August 24 primary.

Rubio is viewed favorably by 72 percent of these GOP voters, compared to 55 percent for Crist. The governor is viewed unfavorably by 44 percent.

Crist would lose by 17 percentage points even if he carried every undecided voter at this point. He would have to plug that gap with Rubio’s supporters, who are unlikely to shift from supporting a conservative candidate to one who campaigned for a failed $825 billion “stimulus” package and continues to support cap-and-trade.

Why has Crist suddenly gone from a loss to a collapse? Well, for one thing, the televised debate on Fox News didn’t help. Crist was hoping to repair his image and tear down Rubio, but he was unable to effectively defend his past or make an argument for the future.

So can Rubio win in the general election? Sure, and that poll takes into account a third-party candidacy by Crist, who insists he won’t run as an independent even if he loses. A young conservative of Cuban descent running in Florida in November 2010? Unless he royally screws up, he should take the seat pretty easily.