The largest state that’s likely to see a seriously contested U.S. Senate race in 2010 is Florida. Democrats Barbara Boxer and Charles Schumer seem safe in California and New York, and neither Texas seat is up. Unless, that is, Republican Governor Charlie Crist runs, an option he has left open.

The latest Quinnipiac Florida poll shows Crist’s popularity running high not only among his fellow Republicans but among Independents and Democrats as well. But there’s a note of caution: a significant 42%-26% plurality of voters would rather see Crist run for reelection as governor. In addition, former state House Speaker Marco Rubio, a Republican, has indicated he’ll run for the Senate whether Crist does or not—a reversal of his previous position. Crist’s entire career has been in state politics, and the issues on which he’s won widespread popularity—a state insurance program, the purchase of USSugar lands to promote Everglades restoration—aren’t going to be particularly relevant in a Senate race.