Because he said he wasn’t running for re-election, I included Rubio as one of the Senate hawks that would be out of office next year in my article for the current issue of TAC. I should have known better than to expect Rubio to stick to what he said. The Post reports that Rubio will run for a second term:

Sen. Marco Rubio will announce Wednesday he will seek re-election to the Senate, reversing a pledge he made a year ago to either assume the presidency or return to private life in Florida, instantly transforming an already competitive race and improving the chances that Republicans can maintain the Senate majority.

Rubio does have obvious and significant advantages over his competitors in the primary in terms of name recognition and fundraising, so he should be able to secure renomination. However, the fact Rubio is getting back into a race that he repeatedly said he wouldn’t enter may create an opening for his remaining opponents. One of them, Carlos Beruff, is looking to paint Rubio as an untrustworthy establishment figure. Rubio has alienated enough Republicans over the last five years that he could have a bit of a fight on his hands in the primary.

The senator has a few serious weaknesses. Rubio didn’t do much for his constituents during his first term, and one of the few things he tried to do–the Gang of Eight bill–blew up in his face. He justified his extensive Senate absenteeism by deriding the importance of being in the Senate, and now he is going to come back and insist that he really wants to go back there. His reputation for opportunism and inconstancy has started catching up with him, and he will have a hard time defending his record of neglecting his job while trying (and failing) to use it as a springboard to higher office.

Rubio probably does give the Republicans a better chance of holding the seat, but it isn’t certain that they will. He polls better against Rep. Patrick Murphy than other Republican candidates because he is better-known, but his support remains below 50%. His best recent approval rating in Florida is an underwhelming 45% (the worst is 30%), and it’s entirely possible Rubio will end up losing the race. The 2016 electorate will be larger and less hospitable to Rubio than the 2010 electorate was, and even in that very good year for Republicans Rubio won a three-way race with just under 49% of the vote. He won’t have the advantage of a Crist independent candidacy splitting the Democratic vote, and this time he will be running with the baggage from his first term and his failed presidential campaign.