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Just two months into President Barack Obama's second term, Republican leaders are lining up to diagnose their party's ills while courting conservative activists ahead of what could be a crowded presidential primary field in 2016.

Die-hard conservatives attending the Conservative Political Action Conference in suburban Washington were already picking their favorites for 2016.

Thousands of activists who attended the gathering gave Kentucky Sen. Rand Paul a narrow victory over Florida Sen. Marco Rubio in their unscientific presidential preference poll. Paul had 25 percent of the vote and Rubio 23 percent.

Former Pennsylvania Sen. Rick Santorum, a favorite of social conservatives who unsuccessfully challenged Mitt Romney for the nomination last year, was third with 8 percent.

Rubio and Paul, both first-term U.S. senators, topped a pool of nearly two dozen governors and elected officials who paraded through the same ballroom stage over three days at the Conservative Political Action Conference. There were passionate calls for party unity, as the party's old guard and a new generation of leaders clashed over the party's future.

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The ballroom stage was emblazoned with the words "America's Future: The Next Generation of Conservatives," making clear the party's interest in showcasing a new wave of talent. The gathering evoked the ending of one period and the beginning of another.

Sharp competition among Republican leadership comes as Obama's role as the head of his party is unquestioned. Even looking to the next presidential election, there is a smaller pool of possible Democratic candidates largely waiting on former Secretary of State Hillary Rodham Clinton to shape her plans. Democrats concede she would be the strong favorite to win her party's nomination if she ran.

There is no such certainty on the Republican side, regardless of the outcome of the conservative straw poll.

Several high-profile Republicans are jockeying for elevated leadership roles.

Earlier in the week, Paul insisted on a new direction in Republican politics: "The GOP of old has grown stale and moss-covered."

The straw poll victory offers little more than bragging rights for Paul, who is popular with the younger generation of libertarian-minded conservatives who packed the conference in suburban Washington. Nearly 3,000 people participated in the online survey and more than half were younger than 26.

Paul's father, former Texas Rep. Ron Paul, won the poll in 2010 and 2011, while presidential nominee Mitt Romney took the honor last year. Ron Paul unsuccessfully competed for the Republican nomination in 2008 and 2012.

Rubio drew thunderous applause by proclaiming that the Republican Party doesn't need any new ideas: "There is an idea. The idea is called America, and it still works," he said in a speech aimed squarely at middle-class voters.

First-term Wisconsin Gov. Scott Walker, who placed sixth in the straw poll, on Saturday encouraged Republicans to be aggressive but also warned them to focus on middle-class concerns: "We need to be relevant."

The Republican gathering also featured Romney, who delivered his first speech since his Election Day loss four months ago on Friday.

He offered a valedictory of sorts, thanking activists for supporting his campaign, while conceding mistakes -- although he didn't offer any specifics. In a nod to the next generation, he urged conservatives to learn lessons from the nation's 30 Republican governors.

Romney heaped praise on his 2012 running mate, Wisconsin Rep. Paul Ryan, while naming a handful of governors who have sought a larger national profile, including Bob McDonnell of Virginia and Chris Christie of New Jersey.

Neither Christie nor McDonnell were invited to the conference after rankling conservatives in recent months for, among other things, supporting efforts to expand Medicaid coverage as part of Obama's health care overhaul.

Most of the candidates have been working to raise their national profiles while tiptoeing around questions about their presidential ambitions.

Walker told The Associated Press late last month that a 2016 presidential bid "would be an option," although it wasn't something he was "actively pursuing."

Paul has said he's "seriously considering" running for the White House. Ryan, the House Budget Committee chairman, has avoided such questions and instead continued his central role in one of Capitol Hill's most significant policy debates.

Another former vice presidential candidate, ex-Alaska Gov. Sarah Palin, mixed anti-Obama rhetoric with calls for a more inclusive Republican Party. "We must leave no American behind," she said after likening Washington leadership to reality television.

Palin took a shot at the president's call for universal background checks on gun purchasers, saying, "Dandy idea, Mr. President -- should have started with yours." She also mocked Michael Bloomberg by sipping soda from a "Big Gulp" cup -- the type of supersized, sugary drink that the New York mayor tried to ban in an effort to fight obesity only to have a judge strike down the restriction.