LATEST DEVELOPMENTS

Syria: The government derided President Barack Obama’s decision to hold off on punitive military strikes, but also took precautions by reportedly moving some troops and military equipment to civilian areas.

Vatican: Pope Francis said he would stage a worldwide prayer vigil for Syria on Saturday and called on all sides to lay down their arms.

United Nations: The organization asked the head of its chemical weapons inspection team to expedite the analysis of tests from samples it collected from Syria last week.

France: Lawmakers said the French parliament should get the same privilege the U.S. Congress will have to vote on Syria intervention.

Israel: Prime Minister Benjamin Netanyahu tried to soothe a jittery nation by saying Israel is “calm and self-assured” and ready for “any possible scenario.”

— Associated Press

The Obama administration geared up for the biggest foreign policy vote since the Iraq war by arguing Sunday that new physical evidence shows the Syrian government used sarin gas in a deadly August attack. With its credibility on the line, the United States must respond, the country’s top diplomat said.

Members of Congress, deadlocked on just about everything these days and still on summer break, expressed sharply divergent opinions about whether to give President Barack Obama the go-ahead he requested to retaliate with military force against the Assad regime, and what turning down the commander in chief could mean for America’s reputation.

Presenting Obama’s case for military action, Secretary of State John Kerry gave a series of interviews Sunday news shows outlining the latest information the administration has received about the Aug. 21 attack in the Damascus suburbs that the U.S. says killed 1,429 civilians, including more than 400 children. He said samples collected by first responders added to the growing body of proof that Syria’s government launched a chemical weapons attack.

“Samples of hair and blood have been tested, and they have reported positive for signatures of sarin,” Kerry said. “Each day that goes by, this case is even stronger. We know that the regime ordered this attack. We know they prepared for it. We know where the rockets came from. We know where they landed. We know the damage that was done afterwards.”

Sarin, which affects the nervous system and is toxic in liquid or gas form, can be delivered in missiles, bombs, rockets or artillery shells. The gas is outlawed under international rules of warfare. The reference to hair and blood samples were the first pieces of specific physiological evidence cited by any member of the administration, which previously spoke only about an unnamed nerve agent.

Kerry’s assertion coincided with the beginning of a forceful administration appeal for congressional support, now that Obama has declared he will await approval from the House and Senate before ordering any cruise missile strikes or other action.

On Capitol Hill, senior administration officials briefed lawmakers in private to explain why the U.S. is compelled to act against President Bashar Assad’s government. Obama, Vice President Joe Biden and White House Chief of Staff Denis McDonough also made calls to individual lawmakers. Further classified meetings were planned over the next three days in preparation for a vote once lawmakers return from summer break, which is scheduled to end Sept. 9.

Sen. John McCain of Arizona, a leading Senate hawk and the candidate Obama defeated for the presidency in 2008, said he’d discuss Syria with the president at the White House today.

Dozens of members attended the two-hour classified briefing Sunday in the Capitol, though many emerged saying they needed to see more details of Obama’s plan and more facts about the alleged chemical weapons attack. Many feared giving Obama overly broad authority for military action.

On selling the strategy to Congress, Rep. Rep. Bennie G. Thompson, the senior Democrat on the House Homeland Security Committee, said, “They have a ways to go.”

“They also have work to do with respect to shoring up the facts of what happened,” Thompson said.

Kerry was asked repeatedly in the broadcast interviews what Obama would do if Congress didn’t give its consent. He said he believed lawmakers would recognize the grave implications for letting a chemical weapons attack go unchecked and what that might mean for U.S. efforts to force North Korea to get rid of its nuclear weapons and prevent Iran from acquiring such capability.

“We are not going to lose this vote,” Kerry said. “The credibility of the United States is on the line.”

Sen. Tim Kaine, D-Va., said Congress and the American people would support action once Obama finishes making his case. Sen. Saxby Chambliss, R-Ga., said if Obama doesn’t do that, he won’t get his authorization.

“He’s got to come out and really be in-depth with respect to the intelligence that we know is out there,” said Chambliss, the top Republican on the Senate Intelligence Committee. “He’s got to be in-depth with respect to what type of military action is going to be taken and what is our current strategy.”

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Obama is likely to find stronger support in the Democrat-controlled Senate than the GOP-dominated House, yet faces complicated battles in each. Some anti-war Democrats and many tea party-backed Republicans are opposed to any intervention at all, while hawks in both parties, such as McCain, feel the president must do far more to help Syria’s rebels oust Assad from power.

“It can’t just be, in my view, pinprick cruise missiles,” McCain told CBS’ “Face the Nation.”

On the other end of the spectrum, an unusual coalition of foreign policy isolationists, fiscal conservatives and anti-interventionists in both parties opposes even limited action for fear that might draw the United States into another costly confrontation.

“I think it’s a mistake to get involved in the Syrian civil war,” said Sen. Rand Paul, R-Ky.