After adopting some of the harder-line positions in his 2010 Senate run, he began work earlier this year on an alternative to the Dream Act. Instead of creating a pathway to citizenship for children of illegal immigrants, Rubio wanted to grant them legal status. Time dragged on and Rubio never produced his plan.

He said he wanted to get it right but the proposal, which he says is still under development, was also under attack from conservatives, who said it was amnesty. Obama stepped in with a directive that gave young undocumented residents protection against deportation. In a sense Rubio was spared, but it also called into question his ability to deliver.

Obama this week said he wants a full immigration overhaul, starting with passage of the Dream Act.

Prominent Republicans say the party must come to the table, but Rubio is taking a careful approach, perhaps unsure how far to brush up against the conservative base that would play a role in his future goals.

He was noncommittal Thursday on a pathway to citizenship for the 11 million undocumented people living in the United States, noting “progress is being made” but saying whatever is done should not “incentivize” more illegal entry. Rubio focused instead on improvements to the legal immigration system, suggesting more workers in agriculture and construction would be needed as the economy improves and saying family unification is key. A spokesman, Alex Conant, said Rubio prefers a “sequential” approach but would not prejudge broader efforts.

Some advisers worry Rubio will be typecast by immigration. “Marco really needs to be outspoken on the issue because of the credibility he has, but he can’t own the issue,” said Al Cardenas, chairman of the American Conservative Union. “He should continue to be a generalist.”

Measured tone

At times, Rubio seems to be trying to construct the perfect, well-rounded candidate, an anti-tax Republican with crossover appeal. He’s been critical of Obama on foreign policy, fiscal issues and health care, but also joined forces with Democrats on a series of lower-end business measures and pursued niche issues such as human trafficking. As early as next month, he will push a package of policies focused on “upward mobility” of poor people.

Rubio, who has drawn praise from colleagues on both sides of the aisle, has also watched his tone. While fellow foreign policy hawk Sen. John McCain railed last week against comments U.N. Secretary Susan Rice gave after the attack on the U.S. consulate in Libya, Rubio was decidedly measured and said he would not automatically block her possible nomination to head the State Department.

“I think if you’re going to have a fair process to evaluate someone, you can’t go in having already made up your mind,” he said at the Washington Ideas Forum on Thursday.

Just a few days earlier, however, Rubio stressed to reporters that he thought Secretary of State Hillary Clinton should be called to testify on what happened, stoking Washington talk of a 2016 showdown. If she runs, Clinton will certainly emerge as a front-runner among Democrats.

A post-election National Journal poll of insiders showed Republicans think Rubio is the strongest candidate for president, followed by Jeb Bush, one of the undisputed heavyweights of Florida politics. During a rally in Miami a week before the election, Rubio and Bush stood on stage with Romney but it was Rubio’s name the crowd shouted, and when it came time to introduce the candidate, Rubio stepped forward.

“I don’t think we’ll see that contest. I know we won’t,” Cardenas said. “I know for a fact one or the other may run but they both aren’t going to run against each other.”

Contact Alex Leary at leary@tampabay.com. Follow him on Twitter @learyreports.