The measure in the Senate Committee on Foreign Relations passed by a 10-to-7 vote — with seven Democrats and three Republicans in favor, and two Democrats and five Republicans opposed — and heads to the full Senate next week.

But in twist that signaled the issue still faces an uncertain outcome, Senator Edward J. Markey, a Massachusetts Democrat, voted "present," choosing not to register his position on the highest-profile issue to come before him since he was sworn in nearly two months ago. He was the only senator to cast a noncommital vote.

WASHINGTON — A Senate committee voted on Wednesday to give President Obama the authority to use military force in Syria, providing momentum to the White House plan to punish President Bashir Assad for allegedly using chemical weapons.


It would authorize a limited military strike against Syria that could not exceed 90 days and prohibit US ground troops from being sent into combat. The House is considering a similar resolution.

Markey's decision to vote "present" meant that he did not support the cause being pushed aggressively by President Obama — and by Secretary of State John F. Kerry, who for nearly three decades held the Senate seat that Markey now occupies.

Markey said he cast his equivocal vote because he wants more time to analyze the situation. He said in an interview that the resolution was written too broadly and allowed for the potential that the United States would become far more entangled in the Syrian conflict.

"My one concern is that we not get on a slippery slope — that we understand all of the steps that this action could lead to," he said. "It's about the resolution being too broad. It's about the need for more information. It's about my worry about a greater involvement in Syria."


Asked why he did not just oppose the authorization, as did some of his colleagues who had similar concerns, he said, "A no vote would have indicated I had sufficient information on which to base the decision. Which I did not."

It was a striking statement, given that he essentially suggested that Kerry — his longtime colleague — has not been persuasive enough to earn his vote. Kerry spent more than three hours testifying before the committee Tuesday, building the administration's case.

Late Tuesday night, several top senators had come to an agreement on a four-page resolution, which was distributed to committee members. But Senator John McCain, an Arizona Republican whose support is seen as crucial, said he opposed the resolution because he wanted to authorize broader action in Syria. On Wednesday, after McCain put forward a modification that could help strengthen the Syrian rebel groups opposing Assad, McCain announced he was satisfied and voted for the resolution.

But Markey was not happy with the final version.

"Many of the members were satisfied. I was not," Markey said. "The resolution was completely rewritten yesterday with many changes and I want to make sure what we vote for on the Senate floor is something that reflects the values of the people of Massachusetts."

Markey said that over the next several days, he plans to examine more classified intelligence and consult with more specialists.

"I want to make sure I make an informed, correct vote," he said. "The people of Massachusetts expect their senators to have analyzed all the facts, and I want to make sure I have all the facts before I cast that vote."


Kerry continued to push Congress to act, returning to Capitol Hill for more testimony, this time before the House Committee on Foreign Affairs. In a news conference in Sweden on Wednesday, Obama tried to make the case to the world that action is needed.

"My credibility is not on the line," he said. "The international community's credibility is on the line. And America and Congress's credibility is on the line because we give lip service to the notion that these international norms are important."

The resolution triggered heated debate in the Senate committee. Supporters contended that the United States had to send a message to Syria.

"Failure to respond to such a blatant violation of longstanding international norms not only signals an acceptance of this atrocity, it also jeopardizes the lives of our service members in combat both today and in the future," Senator Tim Kaine, a Virginia Democrat, said in a statement.

But opponents of the resolution said that striking Syria might bring further turmoil in the volatile Middle East.

"I remain unconvinced that the use of force proposed here will work," Senator Marco Rubio, a Florida Republican, said in a statement. "The only thing that will prevent Assad from using chemical weapons in the future is for the Syrian people to remove him from power. The strike the administration wants us to approve I do not believe furthers that goal. And in fact, I believe US military action of the type contemplated here might prove to be counterproductive."


Markey had called on the White House last week to seek approval from Congress before any military action. He told the Globe last week that he would support "a surgical set of strikes" if they were made against the sites that could be used to launch the chemical weapons.

"I think it is important for the United States to make this statement and to be a leader on this issue," he said in an interview.

Later, after Obama announced his decision to seek congressional support, Markey sounded more noncommittal.

"The aftermath of a US strike on targets in Syria is difficult to predict, with negative consequences that may be beyond our capability to control," Markey said in a statement on Saturday.

He provided few clues of how he was leaning on Tuesday, when he questioned Kerry during hearings before the Senate Committee on Foreign Relations.

"I continue to look forward to additional evidence being presented and my hope is we can act in a way that does not bog us down into the middle of a Syrian civil war," Markey said.

He also asked Kerry to help declassify information to help the public learn more about the situation.

Kerry responded that the administration had already taken unprecedented steps to declassify information but did not want to release details that would reveal intelligence sources.

Markey vowed to make a decision by next week.


"I will be casting a 'yea' or a 'nay' on the Senate floor next week," he said.

Matt Viser can be reached at maviser@globe.com.