This district had been held by Republican Mario Diaz-Balart, who resigned from this seat to run for his brother Lincoln's district after Lincoln announced his retirement earlier this year. Mario calculated that Lincoln's seat was much safer for him, a move largely justified by Democrat Joe Garcia's showing against Mario in 2008--Mario's toughest race to date.
Four years ago, Republicans had over a 20,000 voter registration advantage in FL-25, Mario's old district. This year, Democrats actually held a slight registration advantage. This is largely due to an influx of non-Cuban Hispanics and a younger generation of Cuban Americans who are less likely to vote as their parents have done (for Republicans) and are more open to Democrats.
This race seems to have all the makings of a doozy.
The Democratic candidate is the aforementioned Garcia. Outspent in 2008, Garcia narrowly lost to Diaz-Balart by 7 percent. And though President Obama appointed Garcia to an Energy Department post, it was this strong 2008 showing that had national Democrats urging Garcia to run for this seat. The DCCC added Garcia to its "Red to Blue" program, which supports candidates who can potentially flip seats occupied by Republicans.