Diaz-Balart is the 18th House GOPer to step down, and one of the few who holds a seat that Dems could target. In '08, he defeated Dem Raul Martinez by 16 pointes, even though the DCCC spent money in his Miami-Dade and Broward Co. district.
The district is heavily Hispanic, thanks to Miami's large Cuban population. 73% of district residents call themselves Hispanic, while just 16% are white. Sen. John McCain (R-AZ) won a narrow 51%-49% victory in the seat.
First elected in '92, Diaz-Balart has had little trouble holding on to his seat. His brother, Mario, represents another heavily-Cuban part of Miami. CongressDaily reports that Mario Diaz-Balart will abandon his district to run in Lincoln's, which is seen as tilting more toward the GOP.
A Dem source tells Hotline OnCall that '08 nominee/Dept. of Energy appointee Joe Garcia (D) is considering the race if Mario does indeed leave his district, the 25th, to run in his brother's seat. Garcia had turned down a rematch earlier this year, but appears he may be tempted to enter the open seat.
http://hotlineoncall.nationaljournal.com/archives/2010/02/diazbalart_to_r.php