Sens. Marco RubioMarco Antonio RubioRubio: McCabe 'should've been allowed to finish through the weekend' For Tillerson, bucking Trump became a job-killer At least six dead after pedestrian bridge collapses on cars in Florida MORE (R-Fla.) and Rand PaulRandal (Rand) Howard PaulTrump formally sends Pompeo nomination to Senate Spending bill delay raises risk of partial government shutdown support Overnight Defense: Senate sides with Trump on military role in Yemen | Dem vets push for new war authorization on Iraq anniversary | General says time isn't 'right' for space corps MORE (R-Ky.) previewed a potential 2016 GOP presidential showdown Thursday with back-to-back, dueling speeches offering competing — and starkly different — visions of the Republican Party's future. 

Their highly anticipated speeches to activists at the Conservaative Political Action Conference reflected the broader GOP identity crisis — and the party-wide effort to recalibrate in the face of disappointing losses for the GOP in 2012.

Rubio and Ryan have shared many steps on their roads to success — both Tea Party favorites, they rose to national prominence after elections they won as underdogs. 

But their CPAC speeches indicated they may be pursuing support in different wings of the GOP, paths that could put them on a collision course in time for 2016.

If the CPAC speeches are any indication, Rubio is beginning to find comfort within the establishment wing of the party, while Paul plans to pick up where his father, former Rep. Ron Paul (R-Texas), left off in cultivating and expanding libertarian appeal.

Rubio asserted that the GOP doesn’t “need a new idea, and that “the idea's called 'America' and it still works.” 

But Paul, speaking immediately after Rubio on Thursday afternoon, charged that “the GOP of old has grown stale and moss-covered. He called for a new Republican Party based on the idea of liberty in the public and private sphere.

"I don't think we need to name any names, do we? Our party is encumbered by an inconsistent approach to freedom. The new GOP will need to embrace liberty in both the economic and the personal sphere," Paul said.  

"If we're going to have a Republican Party that can win, liberty needs to be the backbone of the GOP. We must have a message that is broad, our vision must be broad, and that vision must be based on freedom."

Rubio, in his speech, seemed to be laying claim to the social-fiscal-national security-conservatism that is typically the bread-and-butter of the GOP base, and which is the most prominent ideology at CPAC.

"Our people have not changed. The vast majority of the American people are hard-working taxpayers," he said. "Our challenge is to create an agenda applying our principles."

He touched on conservative red-meat issues, defending his opposition to gay marriage and abortion and sounding, at times, like a social conservative in the mold of former GOP presidential candidate Rick Santorum.

"Do not underestimate, I know this movement does not, the impact that the breakdown of the family is having on the American people and our long-term future," Rubio said at one point.

Paul proclaimed his support for the issues that traditionally fire up the libertarian base, built by his father, that is now looking to him. He cited the need to decriminalize nonviolent drug use, and expressed strong support for the Second and Fourth Amendments.

"The Republican Party has to change by going forward to the classical and timeless ideas enshrined in our Constitution. When we understand that power corrupts, and absolute power corrupts absolutely, then we'll become the dominant national party again," he said.

And at times, it seemed like the two senators were anticipating — or responding to — the other's speech, highlighting points of divergence that offer a small preview of what a Rubio-Ryan 2016 presidential debate could look like.

Rubio said that while "we can't solve every war…we also can't be retreating from the world" — a remark that seemed a preemptive response to Paul, who favors a less interventionist U.S. foreign policy.

And Paul at one point said that "the new GOP will need to embrace liberty in both the economic and the personal sphere," echoing a conventional libertarian critique of the mainstream Republican position in opposition to gay marriage and abortion, which Rubio touted in his speech.

Grover Norquist, president of anti-tax-increase group Americans for Tax Reform, wouldn't pick a favorite following the speeches, and didn't indicate which senator he thought performed better. 

"I'm a fan of both of them in many ways," Norquist said.

But he hinted that Paul's message may be a better one for the GOP, going forward.

"I think change and forward is a better way of expressing our commitment to liberty than, 'Isn't that our tradition?'" he said.

However, Paul walks a fine line in aiming to expand the appeal of the libertarian brand his father launched to national prominence, in that he'll need to make headway within the GOP establishment in order to be taken seriously outside it.

To do that, he'll need to be careful not to be too critical of the GOP. 

Matt Mackowiak, a Republican consultant, warns that attack lines like Paul's "moss-covered" barb could ruffle some feathers.

"Within some of the Republican Party there's frustration that some of these guys are criticizing the party. Instead they should focus on Democrats, there's that feeling," Mackowiak told The Hill.

Paul seemed aware of the potential backlash to his criticism, joking to the crowd that he wouldn't "name any names" when criticizing the establishment wing of the GOP.

Paul's differences with old guard Republicans came into stark relief over the past few weeks, following the 13-hour talking filibuster of President Obama's CIA nominee, John Brennan, that brought him national attention. The Kentucky senator filibustered in protest of the adminstration's drone strike policy. 

Sens. John McCainJohn Sidney McCainTrump congratulated Putin after his national security team told him not to: report Trump faces backlash after congratulating Putin on election win McCain rips Trump's congratulatory call to Putin as an insult to Russian people MORE (R-Ariz.) and Lindsey GrahamLindsey Olin GrahamSteyer brings his push to impeach Trump to town halls across the nation Trump formally sends Pompeo nomination to Senate GOP leaders to Trump: Leave Mueller alone MORE (R-S.C.) critized Paul for what McCain characterized as a stunt meant to "fire up impressionable libertarian kids in their college dorms."

Rubio, comparatively, has found a niche within the Republican establishment on immigration, working with Senate leaders behind the scenes on crafting a reform package. 

Neither senator, however, mentioned immigration during their speeches.

Aside from dueling CPAC speeches, the two rising GOP stars have not yet directly clashed on any high-profile issues. Rubio, in fact, supported Paul’s talking filibuster.

But their speeches may preview clashes to come — and if 2016 may be seen as a test of which vision of conservatism resonates with Americans, those clashes could be high-stakes for both.