This article is from the archive of our partner National Journal

To understand the Republican Party's struggles to formulate a midterm agenda, just look at the political trajectory of Marco Rubio.

The senator from Florida, a potential 2016 presidential contender, has calibrated his positions with the prevailing political mood more effectively than any other Republican. He championed immigration reform last year when Republicans thought it was the key to the party's long-term political fortunes, only to now emphasize the Obama administration's unilateral approach in explaining why he no longer supports such efforts. Despite being a longtime foreign policy hawk, he broke with Sens. John McCain and Lindsey Graham so that he could join most other Republicans in denying the president's request to authorize force against Syria. And as a Jeb Bush protege, he supported statewide educational reforms setting high standards for schools, but came out against the Common Core curriculum when the conservative base revolted against specific federal standards.

Political reporters like to use the catch-all phrase "establishment" to describe the GOP's leadership class, but it's important to distinguish party leaders and big-money donors from the strategists who advise the campaigns. Rubio is a product of the latter—the party's influential consultant class. On paper, Rubio checks every box that political operatives pine for—he's young, Hispanic, telegenic, and clear-spoken on both domestic and foreign policy issues. And unlike many of his prospective rivals, he's been articulating his policy vision by focusing on the middle class with economic security, education reform, and classic American values arguments. Those also happen to be the issues swing voters cite as concerns.

But despite his assiduous attention to the public mood, his presidential stock has stagnated over the past year, and it's in part because he's taken the safe, conventional path. His would-be GOP rivals Rand Paul and Paul Ryan have been spending the summer talking about poverty, an unconventional issue for Republicans to be promoting, but one that's scored them leadership points for challenging their party's dogma on the subject. He's given effective speeches on economic policy, but the party's gubernatorial wing—Ohio's John Kasich, Wisconsin's Scott Walker, New Jersey's Chris Christie among them—can actually point to records of accomplishment as executives. Even on foreign policy, his strength in a crowded GOP field, his youth doesn't convey the same sense of gravitas that voters may seek.

Call it the Rubio paradox. On one hand, the senator is better in tune with the public mood than any other Republican mentioned as a 2016 contender. On the other, catering to the fickle nature of voters is a thankless task. Just look at the volatile mood of today's electorate: This summer alone, immigration surged as a top concern in the wake of the border crisis, while voters have rediscovered their inner hawk as the threat of terrorism rises. In this environment, Rubio's receiving a near-perfect vote rating from the Club for Growth while maintaining good graces with party leaders is both an impressive accomplishment and a sign of shameless pandering.

Rubio's advisers push back against the notion that his moves are politically motivated. They point to his advocacy for immigration reform despite resistance from the GOP base, and argued that he's always supported active international engagement even in the face of isolationist sentiment. Later this month, he will be outlining his foreign policy vision at a conservative think tank.

"His basic attitude is that public opinion is ever-changing, and that as a policymaker, all you can do is pursue the best policies that you can. And in the long run, the politics takes care of itself," said Rubio spokesman Alex Conant.

But Rubio's biggest challenge, if he runs for president, is proving that he's more of a statesman than strategist. Since upsetting Charlie Crist in the 2010 Republican Senate primary, Rubio has straddled a line between the tea party and the establishment, relying on his biography to paper over the differences. Yet in Congress, he's never been as bold as he was in his initial decision to challenge the sitting governor.

Now he's going to need some tangible accomplishments to complement the array of speeches that he's been delivering—and it wouldn't hurt if he developed some distance from his party in doing so. If Republicans capture the Senate, he should take on a beefed-up version of immigration reform with renewed vigor, for example, or translate some of his ideas on economic mobility into legislation that could win bipartisan support. (His recent introduction of a student-loan bill, with Sen. Mark Warner of Virginia, is a step in that direction.)

But he hasn't left himself much time. Rubio has already said that he'll leave the Senate after one term if he pursues a presidential campaign, giving him little opportunity for resume-building.

And one lesson Republicans hope voters learned from President Obama's presidency is that it requires more than a few good speeches and a compelling biography to serve in the White House. Rubio has the political talent to compete for the nomination, but he'll need to leave office with a record of accomplishment to be seen more seriously.

CLARIFICATION: Rubio didn't publicly support Common Core standards before coming out against them in July 2013. In a statement outling his opposition to the standards, he called Common Core "a well-intentioned effort to develop more rigorous curriculum standards" but was being used by the Obama administration to "turn the Department of Education into what is effectively a national school board."

This article is from the archive of our partner National Journal.

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