Though no official announcement has been made, Chris Cilliza reports that the Sunshine State’s lone Republican US Senator, Mel Martinez, has decided to not seek a second term in 2010.

According to sources close to Martinez – the former beleaguered General Chairman of the Republican National Committee who resigned amid the comprehensive immigration debate – the retirement was prompted by a desire for “more free time and a less scheduled life.” Martinez’s retirement is sure to start a new parlor game in Floridian politics, ensuring both a costly and competitive primary and general election.

Of the potential candidates:

State Chief Financial Officer Alex Sink, widely seen as Democrats’ strongest potential candidate, has apparently decided that she would not run but may well reconsider that decision given Martinez’s expected announcement today. Democratic Reps. Ron Klein and Kendrick Meek as well as state Sen. Dan Gelber are likely to consider the open seat race.

On the Republican side, there may well be a push to recruit former Gov. Jeb Bush into the contest although that seems like a long shot. State Attorney General Bill McCollum will almost certainly be mentioned as will state Senate President Jeff Atwater and former state House speaker Marco Rubio.