The Great Marco Rubio Recalibration continues.

Months after helping the Senate pass a sweeping immigration reform bill, the junior Republican senator from Florida has dropped his support for the legislation, saying he now favors a targeted, piecemeal approach to the issue.

It's a stunning about-face from earlier this year, when Rubio's soaring rhetoric and tireless efforts helped propel a comprehensive, bipartisan bill to a successful vote. And with that, Rubio risks appearing to have flip-flopped on a defining issue even faster than you can say "Mitt Romney."

With the House resistant to take up a comprehensive immigration bill, Rubio's spokesman on Monday said he believes a piecemeal approach is the only way anything will get done.

"The point is that at this time, the only approach that has a realistic chance of success is to focus on those aspects of reform on which there is consensus through a series of individual bills," Rubio spokesman Alex Conant told Politico. "Otherwise, this latest effort to make progress on immigration will meet the same fate as previous efforts: Failure."

Of course, a piecemeal approach will almost surely doom meaningful reform. The whole point of a comprehensive approach is give each side something they want, such as a pathway to citizenship for Democrats and tougher workplace enforcement for Republicans.

Conant added that Rubio always preferred a piecemeal approach (though many would debate that), but worked with the Gang of Eight anyway "despite strong opposition within his own party and at a significant and well documented political price."

That gets at another force pushing Rubio away from his own bill: Public opinion. Or, more accurately, Republican public opinion.

Rubio's standing within the GOP eroded all year as he was unable to convince skeptical conservatives the immigration bill was more than just amnesty for undocumented workers. Once one of the most popular GOP senators in the country, his approval rating slid into negative territory in his home state, and he fell to the middle of the pack in hypothetical polls of the 2016 GOP field.

To stem the bleeding, Rubio tiptoed away from the bill since its passage in June, saying after the government shutdown that President Obama had "undermined" the bill's odds of passing by refusing to negotiate with Republicans over budget matters. Even before that, he took a backseat in finalizing the bill while two other GOP senators stitched together an almost comically robust border enforcement provision to win over the necessary Republican votes.

Though Rubio may indeed have preferred piecemeal bills all along, his walk-back could wind up earning him a reputation as a pliable opportunist.

"I'm not sure it has ever happened before that an architect of major legislation in the Senate has basically opposed its passage in the House," Rich Lowry wrote in National Review. "The politics of this aren't great for Rubio," he added, saying the freshman senator would surely "take another hit, understandably, for his inconstancy."

Inconstancy, though not unheard of in politics, is not a good habit to form. Accusations of flip-flopping dogged Mitt Romney's presidential campaigns and kept him from winning over dubious voters. He tried to position himself, after years of presenting a moderate exterior, as a "severe conservative" to capture the GOP nomination. And, like Rubio, he ran away from his most visible legislative achievement: RomneyCare.

The move to the right didn't work out so well for Romney, only further cementing his image as a man without convictions.

Rubio hasn't earned himself quite the same reputation, and we're a long way from 2016. But if he makes a habit of spinning with the political winds, the GOP will begin to see him less as the party's savior, and more as the second coming of Mitt Romney.