Sen. Rand Paul, who's already said he opposes the limited U.S. military strikes in Syria being pushed by President Barack Obama, said Sunday he was still weighing his options for stalling a vote in the full Senate on the use of force resolution.
The Kentucky Republican said a filibuster -- which he used earlier this year to demand more information from the Obama administration on the use of drones -- could only delay a vote, but wouldn't "put off a vote forever."
Instead, he said, he'd demand that any vote taken by Congress be binding, meaning that the president would be barred from striking Syria without congressional approval.
"The president cannot, if we vote him down, decide to go to war anyway. That's the way I interpret the Constitution," Paul said on "Fox News Sunday."
Asked Friday whether he would approve military strikes without congressional backing, Obama refused to answer, saying he didn't want to "jump the gun" before lawmakers cast votes.
Presented with the same question Sunday, his chief of staff said Obama's aggressive outreach to lawmakers wasn't without purpose.
"Our consultation with Congress and the president's request for authorization is not an empty exercise," Denis McDonough told CNN's chief political correspondent Candy Crowley on "State of the Union."
Paul, who was elected with strong backing from the tea party movement, wouldn't speculate whether it would be an impeachable offense for Obama to take action in Syria without support from the Congress, but did say Obama "has already proven to go above the law in many instances."
"Whether you impeach someone is another question, and it's obviously a big one. I wouldn't make a judgment on that," he said.