PORTLAND — U.S. Sen. Angus King on Wednesday said he has not yet made a decision on whether to support military intervention in Syria.

“I can tell you that in my years of public service, I think this is just about the most difficult decision I’ve ever had to deal with,” King said during a press conference at the Portland Jetport. King returned to Maine on Wednesday evening after a day in the Capitol, where he received confidential intelligence briefings from the Pentagon and listened in on other briefings with the Senate Intelligence Committee and Senate Foreign Relations Committee.

President Barack Obama has asked Congress to weigh in on his plan for a limited missile strike against the Damascus-based government of President Bashar al-Assad for his suspected use of chemical weapons against civilians. Chemical weapons were made illegal by the Geneva Convention of 1929.

“I am trying to learn as much as I can to understand the ramifications of this question, which are enormous,” King said. “Is there more risk to the national interest in doing nothing or is there more risk to the national interest in acting? That’s the question I think we’re all wrestling with.”

Also on Wednesday, the U.S. Senate Foreign Relations Committee approved a resolution authorizing the use of military force in Syria by a vote of 10-7, with one senator merely voting “present.”

The resolution is narrower than Obama’s proposal and explicitly states that the U.S. will not send ground troops to Syria.

The panel’s action clears the way for a vote on the resolution in the full Democratic-controlled Senate, likely next week. The Republican-led House of Representatives must also pass a version of the measure before it can be sent to the president for his signature.

King reiterated his position that any action in Syria should be supported by the international community. The United Kingdom last week opted not to support intervention, and the United Nations has also stood impotent against Assad thanks to vetoes or threats of vetoes from Russia and China.

“If we’re being called upon to enforce what is characterized as an ‘international norm,’ then there should be international support,” King said. “That doesn’t mean it has to be a ‘who’s who’ of the United Nations, but there should be some strong indications of support internationally.”

King said he hopes a nonmilitary solution to deterring the use of chemical weapons is possible. But despite his reservations for the use of force, the senator said the argument for the limited attacks are sound.

“The argument is that if we turn a blind eye to this use, that we are in fact encouraging not only Assad but other regimes [including Iran or North Korea, he later said] to act irresponsibly with regard to these kinds of weapons. That’s a powerful argument,” King said.

A question that still remains, is what Obama would do if Congress does not sign off on military intervention. The president has argued that he did not need lawmakers’ approval for a strike, but that he sought their input due to the gravity of the decision. It is unclear whether Obama would let loose missiles if Congress disapproved.

King said it would be “a grave mistake” for the president to defy Congress, but he recognized that Obama “has his own agonizing decisions to make.”

“The lack of support in the Congress and in the country, I think, is a good reason to not go ahead,” King said. “Additionally, and you won’t hear me say this terribly often, I was in agreement with Sen. Rand Paul, [R-Kentucky] yesterday, who was at the Senate Foreign Relations Committee and said that If the president comes to us and we say no, and he does it anyway, that makes the whole thing a kind of show. That would be unfortunate.”

Maine’s other Congressional delegates have also yet to decide how they will vote on the Syria question.

Republican Sen. Susan Collins, who sits on the powerful Intelligence Committee, said she has received several confidential briefings on the situation in Syria and will receive more next week. Still, she doesn’t know how she’ll vote.

“At this point, I have not reached a decision on how I will vote on this serious matter,” Collins said in a statement. “I continue to have many questions about the consequences of military action.”

Rep. Chellie Pingree, the state’s Democratic representative from the first Congressional District, is “inclined to vote no on the resolution, but she has committed to listening to the briefings from the President and the administration, and attend a secure briefing on Monday,” said her spokesman, Willy Ritch.

Democratic Rep. Mike Michaud of the second Congressional District has also yet to decide how he’ll vote, said spokesman Ed Gilman. Michaud is scheduled to be briefed next week.