Sen. Marco Rubio, R-Florida, proposed the U.S. provide ammunition to the Syrian opposition Wednesday, warning that the rebels feel "abandoned" by the West.

"I think it behooves us to do everything we can to ensure that the strongest elements in Syria post-Assad are those that are listening to us, can be influenced by us and have a desire not just to keep the Syrian nation together but to respect the rights of the diverse country that Syria is," he said, told an audience at the Washington Institute for Near East Policy.

Rubio said that while there are "plenty of weapons in Syria, what the opposition really needs is access to ammunition. And I think one of the things we can consider, if we can identify a couple of responsible groups, or more responsible groups, that we feel have built capacity, ammunition is something we can provide, which is not weaponry, per se, but is essential to the weaponry."

"I think that's a step that I'm prepared to advocate for, the provision of ammunition to resistance groups within Syria that we think we can build a long-term dialogue with," added Rubio, a member of the Senate Foreign Relations Committee who just returned from the Middle East.

Rubio, who is frequently mentioned as a possible contender for Republican presidential nomination in 2016, said the Syrian opposition felt the West in general, "and the US in particular has abandoned them."

The opposition, he said, is in favor of democracy and freedom "so they rise up to exercise that, they take out a really bad person in Assad and basically fight for the principles that we say our nation's founded on and we do nothing, we abandon them. That's the sense they have."

His comments come amid reports the Obama administration is considering giving non-lethal military aid to the opposition, including equipment like body armor and armored vehicles. He said once Syrian President Bashar al-Assad falls, the most well-armed and organized factions will be anti-American extremists.

"The goal is this," Rubio said. "We should want the best-organized, best-equipped and most dominant groups in the opposition to be groups that are friendlier to our national interests than some of the other elements that are involved."

He also noted the fall of Assad would be a crippling blow to Iran, calling it the "ultimate sanction" again Tehran.