The Shark Tank was hinting yesterday about a major endorsement to come next week, although I wasn’t sure if that was an April Fools joke or not. And if it wasn’t, I figured the obvious suspects were Palin or, more importantly, Jeb Bush.

Surprise.

Former New York Mayor Rudy Giuliani will campaign with Senate candidate Marco Rubio.

The two will appear together Monday in Miami, where Giuliani is expected to endorse Rubio in the Republican primary against Gov. Charlie Crist.

In a statement released by the Rubio campaign, Giuliani said, “Marco Rubio is one of the Republican Party’s true rising stars. He’s a bold leader who will bring common sense to Washington where it’s badly needed.”

Why is one of the party’s most famous RINOs siding against the moderate in the race? Let’s join Mark Halperin and John Heilemann on the campaign trail in 2007…

In July, ’07, Crist visited with Giuliani in the Hamptons: “I’d like to support you,” Crist said.

The next day, Giuliani shared the news with his aide Tony Carbonetti. “I think we got him; it went very well,” Giuliani said.

Carbonetti was familiar enough with Giuliani’s lexicon to know what that meant: Rudy thought it was a done deal. Seeing Giuliani’s strong poll numbers in Florida, Crist had apparently concluded that Rudy was the horse to ride. Carbonetti, a no-nonsense fixer who’d been Rudy’s chief of staff at City Hall, followed up with Crist’s main political guy, George LeMieux, flying to Tallahassee to meet with him and plan the endorsement.

You know what happened after that. A question for Floridians (or those familiar with Florida politics): Laying aside the obvious enjoyment of watching this revenge gambit play out, will this actually help Rubio? My hunch is it will a little, not only because of the number of New York retirees down there but because it helps take the edge off the criticism that Rubio’s some kind of “radical right-winger” or whatever. Although, granted, you’re more likely to hear that charge in the general election campaign, not the primary.

Exit question: When does Rubio roll out the inevitable Palin endorsement? Or, with Florida being a swing state, is that one he’d maybe rather not have?