WASHINGTON— In an impassioned appeal for support both at home and abroad, President Barack Obama said Wednesday the credibility of the international community and Congress is on the line in the debate over how to respond to the alleged use of chemical weapons in Syria. As Obama made his case overseas during a visit to Sweden, his proposal for military intervention was under consideration by skeptical members of Congress.

Asked about his own past comments drawing a “red line” against the use of chemical weapons, Obama said it was a line that had first been clearly drawn by countries around the world and by Congress, in ratifying a treaty that bans the use of chemical weapons.

“That wasn’t something I just kind of made up,” he said. “I didn’t pluck it out of thin air. There’s a reason for it.”

Obama said that if the world fails to act it will send a message that despots and authoritarian regimes “can continue to act with impunity.”

“The moral thing to do is not to stand by and do nothing,” he declared at a news conference in Stockholm with Swedish Prime Minister Fredrik Reinfeldt.

With Obama in Europe, the president’s top national security aides were briefing legislators in a series of public and private hearings, hoping to advance their case for limited strikes against Syrian President Bashar Al-Assad’s regime in retaliation for what the administration says was a deadly sarin gas attack by his forces outside Damascus last month.

Abhorrent act

The Senate Foreign Relations Committee responded Wednesday by authorizing the use of force for 60 days, with no U.S. troops on the ground in Syria.

It is the first in a series of votes as the president’s request makes its way through Senate and House committees before coming before the two chambers for a final vote.

In a sign of the complicated dynamics at play on Capitol Hill, however, Sen. John McCain, R-Ariz., an outspoken advocate of intervention, said he wants more than cruise missile strikes and other limited action. McCain subsequently voted in favor of the committee resolution, a possible indication that he may have won such assurances from the president.

Sending a message to Congress from afar, Obama insisted there was far more than his own credibility at stake.

“I didn’t set a red line, the world set a red line,” he said. “The world set a red line when governments representing 98 percent of world population said the use of chemical weapons is abhorrent.” He added that “Congress set a red line when it ratified that treaty.”

Obama got welcome support from abroad, as French Prime Minister Jean-Marc Ayrault told the French parliament that failure to react would allow Assad to launch a similar attack again.

The Senate Foreign Relations Committee’s top members drafted the resolution late Tuesday that permits Obama to order a “limited and tailored” military mission against Syria, as long as it doesn’t exceed 90 days and involves no American troops on the ground for combat operations.

“We have pursued a course of action that gives the president the authority he needs to deploy force in response to the Assad regime’s criminal use of chemical weapons against the Syrian people, while assuring that the authorization is narrow and focused,” said the committee’s chairman, Sen. Bob Menendez, D-N.J., who drafted the measure with Sen. Bob Corker of Tennessee, the panel’s senior Republican.

“We have an obligation to act, not witness and watch while a humanitarian tragedy is unfolding in plain view,” Menendez said.

Asked whether he would take action against Syria if he fails to get approval from Congress, the president said his request to lawmakers was not “an empty exercise” but that as commander-in-chief “I always preserve the right and the responsibility to act on behalf of America’s national security.”

To get a green light from Congress, Obama needs to persuade a Republican-dominated House that has opposed almost the entirety of Obama’s agenda since seizing the majority more than three years ago. Several conservative Republicans and some anti-war Democrats already have come out in opposition to Obama’s Syria plan, even as Republican and Democratic House leaders gave their support to the president Tuesday.

House Speaker John Boehner emerged from a meeting at the White House and declared that the U.S. has “enemies around the world that need to understand that we’re not going to tolerate this type of behavior. We also have allies around the world and allies in the region who also need to know that America will be there and stand up when it’s necessary.”

Rep. Eric Cantor, the House majority leader, also backed action. But he acknowledged the split positions among both parties and said it was up to Obama to “make the case to Congress and to the American people that this is the right course of action.”

Secretary of State John Kerry, Defense Secretary Chuck Hagel and the chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey, were trying to make that argument in a public hearing before the House Foreign Affairs Committee on Wednesday. They and other senior administration officials were also providing classified briefings to the Senate Foreign Relations and Armed Services committees.

A consistent refrain in Tuesday’s Senate hearing was the need for clearer limits on the duration and scope of any resolution that authorizes military force. Chief among them was language barring American soldiers from being sent to fight in Syria, something Obama has said repeatedly he has no intention of doing.

“There’s no problem in our having the language that has zero capacity for American troops on the ground,” Kerry told lawmakers. “President Obama is not asking America to go to war.”

Momentum gained

The administration says 1,429 people died from the chemical attack on Aug. 21 in a Damascus suburb. The British-based Syrian Observatory for Human Rights, which collects information from a network of anti-government activists in Syria, says it has been compiling a list of the names of the dead and says its toll has reached 502.

Assad’s government blames the episode on the rebels. A United Nations inspection team is awaiting lab results on tissue and soil samples it collected while in the country before completing a closely watched report.

Obama, who arrived in Stockholm early Wednesday, was hoping to maintain the momentum toward congressional approval that he has generated since Saturday, when he announced he would ask lawmakers to authorize what until then had appeared to be imminent military action against Syria.

Highly skeptical

On Monday, the president met privately at the White House with the Senate’s two leading Republican hawks, McCain and Lindsey Graham of South Carolina, and persuaded them to support his plans for an intervention on condition that he also seek to aid the Syrian rebels seeking to oust Assad.

A day later, he sat down with Boehner, Cantor and several other senior lawmakers to make a similar case that Assad must be punished for breaching the nearly century-old international taboo of using chemical weapons. After gaining significant support, Kerry, Hagel and Dempsey appeared to get the backing of most senators at Tuesday’s hearing.

“You’re probably going to win” Congress’ backing, Rand Paul of Kentucky, a conservative senator and likely opponent of the measure, conceded in a late-afternoon exchange with Kerry.

However, even proponents of military action urged Obama to do more to sell his plans to an American public that is highly skeptical after a decade of war in Iraq and Afghanistan.

Obama, who will travel from Sweden’s capital to an economic summit in St. Petersburg, Russia, this Thursday, has little international support for action right now. Among major allies, only France has offered publicly to join the United States in a strike, although President Francois Hollande says he’ll await Congress’ decision.

Always hopeful

Obama had canceled a one-on-one meeting in Moscow with Russian President Vladimir Putin amid tensions over Russia’s granting of asylum to National Security Agency leaker Edward Snowden.

In a wide-ranging interview Tuesday with The Associated Press, Putin expressed hope that the two would have serious discussions about Syria and other issues in St. Petersburg. Putin has warned the West against taking one-sided action in Syria but also said Russia “doesn’t exclude” supporting a U.N. resolution on punitive military strikes if it is proved that Damascus used poison gas on its own people.

Obama, for his part, said that he is “always hopeful” that Putin will change his position on taking action in Syria.

Julie Pace reported from Stockholm, Sweden. Associated Press writers David Espo, Josh Lederman, Donna Cassata, Alan Fram, Jennifer C. Kerr and Lolita C. Baldor contributed to this report.