Rand Paul, Marco Rubio Show Off Foreign Policy Cred in John Kerry Hearing

Aspiring conservative presidential candidates differ on foreign policy.

Republican Sens. Marco Rubio of Florida, left, and Rand Paul of Kentucky hold significantly different foreign policy philosophies.

Sens. Marco Rubio of Florida, left, and Rand Paul of Kentucky represent the new guard of the Grand Ol' Party.

By SHARE

Tea Party favorites and potential 2016 presidential rivals Sens. Rand Paul and Marco Rubio showed clues on how they might differ as candidates in a Republican primary Thursday during the confirmation hearing for Massachusetts Sen. John Kerry as Secretary of State.

Both Paul, of Kentucky, and Rubio, of Florida, offered critiques of the Obama administration's handling of the Libyan conflict but offered differing rationales.

Rubio, who has worked to build mainstream appeal without sacrificing his conservative principles or popularity, told Kerry he wished the United States had been more aggressive during the initial Libyan conflict.

[READ: Paul Threatens to Filibuster Aid to Pakistan]

"I was not suggesting that the U.S. should have invaded or put soldiers on the ground," Rubio said. "We did certain things in the first 48 to 72 hours of that conflict – had we extended that for a couple weeks that conflict would have ended a lot sooner. In hindsight, a shortened conflict there would have certainly led to a government that would have been stronger and less instability than exists now."

But Paul, who has earned a reputation for not being afraid to place himself out-of-the-mainstream on a variety of issues, opposed America's Libyan intervention on constitutional grounds.

"[Obama] took us to war in Libya without congressional authority, unilaterally," he said. "I would argue though that the Constitution really has no exceptions for when you are having a tough time or people disagree with you, that you just go ahead and do it."

[RELATED: Top 2016 Presidential Contenders]

Paul also pointed out that in 2008, then-candidate Barack Obama shared his opposition to presidents unilaterally going to war, and that Kerry himself had spoken out against U.S. involvement in Cambodia in the 1970s on the same grounds.

"The Constitution doesn't really give this kind of latitude to sometimes go to war and to sometimes not go to war," Paul said. "I thought [candidate] Barack Obama was very explicit, it's what I liked about him frankly. People are like, 'oh, Rand Paul certainly doesn't like anything about Barack Obama,' I did like his forthrightness when he ran for office and said 'no president should unilaterally go to war, the Constitution doesn't allow it.'"

Kerry refuted Paul's assertion that there were parallels between what happened in Cambodia and what is happening in Libya and defended the Obama administration's actions.

[WATCH: Clinton Faces Down Senate Panel]

"You can be absolutist and apply it to every circumstance, the problem is, it just doesn't work in some instances," Kerry said, adding that as a senator, he supported unilateral action taken by President Ronald Reagan in Grenada, President George H.W. Bush in Panama and President Bill Clinton in Bosnia.

"When 10,000 people are about to be wiped out by a brutal dictator and you need to make a quick judgment about engagement, you certainly can't rely on a Congress that has proven itself unwilling to move after weeks and months sometimes," Kerry said.

It's obvious Paul – whose father, former Texas Rep. Ron Paul, was unafraid of standing alone on issues – is consciously stoking issues designed to appeal to the most conservative voting bloc. It will ensure he inherits the passionately loyal support his father's purity also cultivated, but may not bode well for his chances of ever winning the White House. Rubio, on the other hand, appears to be working hard to thread the needle of proving to be unquestionably conservative but without losing mainstream credibility and appeal.

More News: