Marco Rubio surprised some observers Wednesday when he voted in the Senate Foreign Relations Committee against a resolution authorizing President Obama to use U.S. military force in Syria. The surprise came not because Rubio had been beating the drum for war earlier — he hadn't — but because he has in the past used foreign policy statements to express deep concerns not only about the Syrian situation but also about Iran's nuclear ambitions. Those concerns seemed to mirror the positions of Senate colleagues John McCain and Lindsey Graham, two of the most strident hawks on the Syria issue, so there were perhaps some assumptions that Rubio would vote in favor of military intervention.

There was also talk about a political motivation. Some critics suggested that Rubio voted "No" to curry favor with a Republican base that he had alienated during the fight for comprehensive immigration reform. "Rubio manages to make himself look juvenile, afraid of base after immigration," tweeted the Washington Post's Jennifer Rubin on Wednesday. "Not presidential in the least."

But in explaining his vote, Rubio said his position is nothing new. "While I have long argued forcefully for engagement in empowering the Syrian people, I have never supported the use of U.S. military force in the conflict," Rubio said. "And I still don't. I remain unconvinced that the use of force proposed here will work."

Later, Rubio aides pointed to earlier statements -- made before Rubio got in trouble with the GOP base over immigration -- in which the senator expressed similar opinions about Syria. For example, in one, an appearance at the Washington Institute for Near East Policy in February of this year, Rubio expressed concern that Syria could become "a sort of Libya on steroids." Discussing the issue of whether the U.S. should arm the rebels, Rubio proposed a halfway measure. "We don't have to give them weapons," he said. "I think they have plenty of weapons, quite frankly. What the opposition really needs is access to ammunition. They run low on that very quickly … That's a step that I'm prepared to advocate for, the provision of ammunition to resistance groups within Syria that we believe we can build a long-term dialogue with."

Nevertheless, Rubio made clear that he did not support any U.S. military action in Syria. "We're not talking about American troops on the ground," he said. "We're not talking about U.S. air power, we're not talking about sending American soldiers or even American trainers into Syria. We're talking about providing ammunition. That's all we're talking about doing."

Rubio's office also pointed to a long list of statements going back to 2011 in which Rubio advocated a variety of measures against Syria -- mostly sanctions against the Assad regime -- but not any sort of U.S. military action. "I describe Rubio's foreign policy as being somewhere in between Rand Paul and John McCain," said one aide Wednesday. "He's not an isolationist, but he's very cautious about engaging militarily overseas." Rubio's committee vote on Wednesday against the Obama intervention resolution, the aide said, is entirely consistent with Rubio's long-held positions.

There's no doubt Rubio hurt his political prospects with the Republican base by taking a leadership role in the legalization-first Gang of Eight Senate immigration bill. Just last week, he was heckled over the issue at a conservative conference in his home state of Florida. But it doesn't appear that his Syria vote was an about-face from previous positions in an effort to regain favor with a Republican base opposed to Obama's proposal. Rather, it was in line with what Rubio has been saying all along.