After denouncing comprehensive reform in his 2010 senate victory, he has done a somersault of Romneyesque proportions, to the chagrin of the GOP base

When Mitt Romney ran as a strongly pro-choice Republican candidate for governor of Massachusetts in 2002, and then ran as a strongly pro-life candidate for the GOP presidential nomination just a few years later, he sowed doubts about his consistency that damaged his chances to win higher office. And not just with Republicans for whom abortion is a defining issue; a complete 180 on a matter of such consequence raised questions about Romney's core beliefs on everything. He never fully recovered.

Now another prominent Republican politician with national ambitions, Sen. Marco Rubio, has changed positions in a dramatic way on another consequential issue. Rubio ran as a conservative favorite in the 2010 Florida Senate contest in part by denouncing plans for comprehensive immigration reform, which he dismissed as "amnesty." Now, just a few years later, he is leading the charge to enact just such a plan.

In that 2010 race, Rubio's opponent, Charlie Crist, spoke favorably of the McCain-Kennedy comprehensive reform proposal that had failed a few years earlier, in 2007. Crist especially endorsed what he called the "earned path to citizenship" in the defeated bill.

"I'm not for amnesty," Crist said in an October 24, 2010 debate with Rubio. After first securing the border, Crist explained, "people should have to get in the back of the line, pay a fine if necessary, their back taxes, and be able to become productive members of the American economy."

Absolutely not, answered Rubio. "'Earned path to citizenship' is basically code for amnesty," he told Crist. "It is unfair to the people that have legally entered this country to create an alternative pathway for individuals who entered illegally and knowingly did so."

Now, less than three years later, Rubio is leading a comprehensive immigration reform effort and advocating a path to citizenship for people who knowingly entered the United States illegally. To travel that path, he stresses, the border must be secured and illegal immigrants in the U.S. must "get in the back of the line, pay a fine, pay taxes."

Does that sound familiar? Any reasonable reading of Rubio's positions then and now leads to the conclusion that he has executed a flip-flop of Romneyesque proportions. Rubio's flip-flop is even worse politically. While Romney switched to a position that was popular with the Republican base, Rubio has done just the opposite.

Rubio denies the charge. During an appearance on "Meet the Press" in April, he explained that back in 2010 he opposed a "blanket amnesty." Today's Gang of Eight bill, he continued, "is not blanket amnesty." In response to an inquiry Monday, Rubio's Senate spokesman added that "Sen. Rubio opposed the 2007 immigration reform -- and his position has not changed."

Rubio's rapid evolution has baffled some of the people who rallied to his support in 2010. "He came across as the genuine article who believed things to his core, a passionate, from-the-heart principled conservative who spoke with conviction," says one Republican who helped promote Rubio's Senate candidacy when few establishment GOP figures supported him. "And immigration was not a small issue. It was so front and center in the 2010 campaign that it does create a certain level of distrust on other issues."

Feelings like that could lie behind Rubio's falling approval numbers among Republican voters. Back in February, not long after Rubio announced the Gang of Eight immigration proposal, 73 percent of Republicans surveyed by pollster Scott Rasmussen had a favorable impression of the Florida senator. In a new Rasmussen survey released Monday, that number had fallen to 58 percent -- a 15-point drop.

Moreover, the intensity of support among Republicans who still view Rubio favorably has also dropped. In February, 44 percent of Republicans had a very favorable opinion of Rubio. Today the number is less than half that -- 21 percent.

A recent talk with conservative Republican activists in Iowa, where 2016 presidential hopes face their first test, gave a human dimension to those sliding numbers. Some felt deeply disappointed. "Rubio seems to be so damaged it will be very difficult for him to recover here in Iowa," said Rep. Steve King, an influential figure in the state caucuses. Others were less negative but made clear that Rubio has now become a polarizing figure in Republican circles. "I am not ready to write him off," said influential Iowa blogger Craig Robinson. "Sure, it's not going to endear him to the Steve King loyalists in the state, but he is still someone that people generally like and respect."

Back in 2008, and again in 2012, Romney's opponents never let him forget the flip-flop that marked his move to the national political stage. In coming years, the same might become true for Marco Rubio.

Byron York, The Washington Examiner's chief political correspondent, can be contacted at His column appears on Tuesday and Friday on