In fact, despite his status as the Republican Party establishment's next big thing and his role in shepherding an immigration reform compromise, Rubio has amassed one of the most conservative records in the Senate in his first two years.
In the National Journal's 2011 vote rankings, Rubio ranked as the 13th most conservative senator, while Heritage Action's scorecard has Rubio as the third most conservative in the 112th congress, behind only now-former senator Jim DeMint (R-S.C.) and Sen. Mike Lee (R-Utah).
Rubio is also one of just nine senators who got a perfect 100 from the American Conservative Union in 2011, and he was one of just five to earn an A+ from the conservative group Americans for Prosperity.
And Rubio has really shown his conservative colors in recent weeks. He was one of just five Republicans to vote against the so-called "fiscal cliff" deal on New Year's Day and voted against the Hurricane Sandy relief bill (instead voting for a smaller version) and against the three-month debt ceiling delay.
Rubio was also one of just 19 Republican senators to vote against another debt ceiling deal in August 2011 and was one of just 12 Republicans to vote against a continuing budget resolution in September of that year.
But his conservatism isn't limited to fiscal issues. He also sponsored a bill last year that would have allowed companies to decide whether they would cover contraception for their employees.
None of this should be terribly surprising from a guy who got his start as the tea party-backed alternative to then-Florida governor Charlie Crist in the 2010 Florida GOP Senate primary.
But while Rubio has been labeled as a tea partier, he has never really exemplified the kind of fire-breathing, anti-compromise image that many tea partiers have. Much of that, undoubtedly, is because he's hardly a newcomer to politics, having served as speaker of the Florida state House while in his mid-30s. Most others identified as tea partiers have considerably less political experience (or none).
In addition, Rubio comes from a swing state in which other politicians might have tacked to the middle in hopes of avoiding a tough challenge in their next reelection campaign.
But good politicians can tend more toward the ideological extreme and do just fine. Case in point is Obama, who had ranked as the most liberal senator, yet had built a public image as someone who want to facilitate compromise.
Even when Obama ran for president, it was hard for Republicans to label him an extremist because it was so at odds with his public image.
Rubio is walking very much the same line, voting very conservative but not coming across as an ideologue and taking care to find middle ground on a signature issue: immigration. And even while he's done that, he's somehow convinced some of the most conservative voices in the party to soften their hard-line stances on that issue -- a tribute to his political skills.
Votes like the one against the Violence Against Women Act, of course, will always be fodder for Democrats in future campaigns — be they in Florida or nationally. But Rubio has done a good job of straddling both the tea party and establishment worlds over the past couple years.
His continued ability to do that (or not) will say a lot about his presidential prospects in 2016.