Results are still coming in from South Carolina’s Democratic primary, but elsewhere, the campaign continues at full steam.

On Tuesday, Florida voters go to the polls in their own primary, which may prove pivotal in the Republican race. (Democrats punished the state for violating the rules laid down by the party, and so candidates have — nominally, at least — stayed away, and the Florida vote won’t technically count in the Democratic race.) Tonight, the state’s governor, Charlie Crist, threw his weight behind Arizona Sen. John McCain.

How much endorsements like this really matter in the minds of voters is always a question up for debate, but the other campaigns had reportedly been courting Crist as well. And he is popular in the state; polls have shown the governor’s approval ratings consistently above 60 percent this year.

Salon reporter Mike Madden, who’s down in Florida covering the race, just got this from Mitt Romney’s spokesman, Kevin Madden (no relation): “Gov. Crist is a good man and a good governor, but of paramount importance to us is that we get the endorsement of Republican voters on Tuesday, and that’s what counts.”

Update:Our Mike Madden has more from the McCain camp, which is trying to decide whether and how Crist will work the campaign trail over the next couple days. He adds: McCain advisors expect the endorsement to dominate news coverage on Sunday, and hope the nod from the overwhelmingly popular governor will shift momentum their way in a very tight race.

It’s also worth noting that Florida Sen. Mel Martinez also endorsed McCain today.