But on Tuesday, Rubio was reelected to a second term in the Senate, and Florida became one less race Republicans have to worry about in their still-to-be-determined battle to keep control of the Senate.
If Hillary Clinton wins, Senate Democrats need to pick up four seats to retake the majority; so far Republicans are holding them off as best they can. In addition to Rubio's win in Florida, Sen. Rob Portman (R-Ohio) just won reelection. And in Indiana, Rep. Todd Young (R) kept the open seat red despite a formidable challenge from former Democratic senator and governor Evan Bayh. In Illinois, Sen. Mark Kirk (R) lost reelection to Rep. Tammy Duckworth (D), which was an expected loss.
Add it all up and Democrats still need to win three more seats to take the majority. Now Florida will not be one of them.
Florida's results are thanks to some seriously good negotiating skills by Senate Majority Leader Mitch McConnell (R-Ky.) and team. They put so much energy into recruiting Rubio because they think he'll play a critical role in helping them keep control of the Senate.
The thinking went something like this: Rubio's star power, his experience and — perhaps most importantly — his ability to raise a lot of money kept the Senate race in Florida competitive during an otherwise tough year for Republicans. And Rubio's fundraising ability and campaign experience would let Senate Republicans focus their energy and money on other close races in states such as Pennsylvania and New Hampshire.
It worked. Rubio's decision to do an about-face and run for reelection immediately cleared out most of the lackluster GOP field. At The Fix, we downgraded the Senate race in the state from third most likely to flip parties to eighth and then to ninth as Senate Democrats decided to spend their money elsewhere rather than this expensive state.
Rubio's reelection was not a given. Many polls showed Rubio neck and neck with Democratic Rep. Patrick Murphy even after Senate Democrats' campaign arm pulled out in mid-October.
And Rubio had his own bruises. He's just months off a failed presidential race where his own state voted for Donald Trump instead of him. (Rubio has since said he'll support Trump.) Then there's the matter of his Senate voting record, one of the worst in Congress in 2015, and that an editorial in one of Florida's largest newspapers called on Rubio to step down.
Rubio also had to explain to voters why he went back on his decision not to run for reelection. (He originally got out to run for president.)
I have only said like 10000 times I will be a private citizen in January.— Marco Rubio (@marcorubio) May 17, 2016
And he needed to make a persuasive pitch for why Florida voters should send him back to Washington when he's not willing to commit to a full, six-year term. He struggled to answer that question in debates. And about 53 percent of Florida voters said they thought Rubio was running for Senate so that he can run for president, according to an August Monmouth University poll. (2020 is in four years, for anyone who's counting.)
But for Senate Republicans, the Florida race was still a contest purely thanks to Rubio.