Sen. Mel Martinez (R-Fla.) announced this morning at an Orlando press conference that he will not run for re-election in 2010.

"The inescapable truth, for me, is that the call to public service is strong, but the call to home, family and lifelong friends is even stronger," Martinez said, according to a press release. "So today, with deep love for this country and with sincere gratitude to the people who placed their trust in me, I announce that I will not run for reelection to the United States Senate."

In 2001, Pres. Bush appointed Martinez as secretary of the Department of Housing and Urban Development, where he served for two years. Despite interest in running for governor in 2006, Martinez was talked into running for the open Senate seat in 2004, which he won by a tight 49%-48% margin over Betty Castor.

Politico's Josh Kraushaar lists some possible candidates to run for this now-open Florida Senate seat:

Democrats had already been considering taking on Martinez before his retirement announcement. Popular state CFO Alex Sink decided not to challenge Martinez over the Thanksgiving holiday, but may now reconsider given Martinez's decision. Other potential Democratic candidates include: Reps. Ron Klein, Allen Boyd and state senator-elect Dan Gelber.

Florida Attorney General Bill McCollum, Rep. Adam Putnam (R-Fla.), Rep. Connie Mack (R-Fla.) and state Senate President Jeff Atwater are all potential Republican candidates.