Florida Sen. Marco Rubio's decision to seek the Republican presidential nomination and thus forgo a re-election bid creates the second open GOP seat of the cycle. It also becomes the first Republican seat in the Toss Up column. Had Rubio run for re-election, he would have started the race as the favorite, but an open seat in a swing state in a presidential year will be a much more competitive contest. On the Democratic side, U.S. Rep. Patrick Murphy has already announced his candidacy, but he is likely to get a challenge from a more progressive candidate. U.S. Rep. Alan Grayson is contemplating the race and would certainly run to Murphy's left. Republicans seem destined to hold a primary of their own. State CFO Jeff Atwater was thought to be the frontrunner, but it does not appear that he will run. U.S. Rep. Ron DeSantis is expected to announce his candidacy soon, while Lt. Gov. Carlos Lopez-Cantera and state House Speaker Will Weatherford are also thought to be likely candidates. Former U.S. Sen. George LeMieux and U.S. Reps. Vern Buchanan,

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