WASHINGTON, D.C. -- President Barack Obama, working to persuade skeptical lawmakers to endorse a U.S. military intervention in civil war-wracked Syria, hosted two leading Capitol Hill foreign policy hawks for talks and directed his national security team to testify before Congress in a determined effort to sell his plan for limited missile strikes against Syrian President Bashar Assad's regime.
After changing course and deciding to seek congressional approval for military action, Obama is confronted with one of his most difficult foreign policy tests and faces a Congress divided over the unavoidably tough vote-of-conscience on overseas conflict rather than the more customary partisan fights over domestic policy.
Lawmakers from both parties have expressed an array of views -- from opposition to any military intervention to a desire for even more robust action than that envisioned by the president.
Sen. John McCain, Obama's White House opponent in 2008, was joined at the White House meeting Monday afternoon by Sen. Lindsey Graham of South Carolina. Graham, like McCain, has argued that Obama must not only punish the Syrian regime with surgical missile strikes but must seek to change the course of the civil war and oust President Bashar Assad from power.
On Tuesday afternoon, Secretary of State John Kerry, Defense Secretary Chuck Hagel and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, are scheduled to testify publicly before the Senate Foreign Relations Committee. Earlier Tuesday, other members of the administration's national security and intelligence teams were to hold a classified, closed-door briefing for all members of Congress. A similar session was held Sunday and more will be held Thursday and Friday.
Kerry will also testify Wednesday before the House Foreign Affairs Committee. Kerry and Director of National Intelligence James Clapper will hold a classified briefing Wednesday with members of the Senate Foreign Relations Committee.
Members of the House Democratic caucus participated in an unclassified conference call Monday with Obama national security adviser Susan Rice, Kerry, Hagel, Clapper and Dempsey.
Obama has said he wants limited military action to respond to an attack in the Damascus suburbs last month that the U.S. says included sarin gas and killed at least 1,429 civilians, more than 400 of whom were children.
McCain and Graham, both Republicans, represent the most aggressive faction in Congress and have called on Obama to launch more comprehensive strikes with an aim of destroying President Bashar Assad's air power, his military command and control, Syria's ballistic missiles, and other military targets while at the same time increasing training and arming of opposition forces.
On the other side of the spectrum, some Republican and Democratic lawmakers don't want to see military action at all.
"I think it's very early for a lot of people and I think people are skeptical because they're hearing questions at home and they are surprised that the president decided to come to Congress," said Rep. Eliot Engel of New York, the top Democrat on the House Foreign Relations committee. Engel, appearing on CNN, says he supports Obama's position but said the president has to make his case to Congress.
The White House is engaging in what officials call a "flood the zone" persuasion strategy with Congress, arguing that failure to act against Assad would weaken any deterrence against the use of chemical weapons and could embolden not only Assad but also Iran and the Lebanese militant group Hezbollah.
Obama's turnabout decision to seek congressional authority on Syria sets the stage for the biggest foreign policy vote in Congress since the Iraq war.
On Sunday, Kerry said the U.S. received new physical evidence in the form of blood and hair samples that shows sarin gas was used in the Aug. 21 attack. Kerry said the U.S. must respond with its credibility on the line.
"We know that the regime ordered this attack," he said. "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."
On Capitol Hill Sunday, senior administration officials briefed lawmakers in private to explain why the U.S. was compelled to act against Assad. Obama, Vice President Joe Biden and White House Chief of Staff Denis McDonough also made calls to individual lawmakers.
"The American people deserve to hear more from the administration about why military action in Syria is necessary, what it will achieve and how it will be sufficiently limited to keep the U.S. from being drawn further into the Syrian conflict," said Sen. Bob Corker of Tennessee, the top Republican on the Foreign Relations Committee, reflecting a more cautious approach to a military strike.
McCain said Obama asked him to come to the White House specifically to discuss Syria.
"It can't just be, in my view, pinprick cruise missiles," the Arizona Republican told CBS' "Face the Nation."
In an interview with an Israeli television network, he said Obama has "encouraged our enemies" by effectively punting his decision to Congress. He and Graham have threatened to vote against Obama's authorization if the military plan doesn't seek to shift the momentum of the 2 1/2 year civil war toward the rebels trying to oust Assad from power.
Obama is trying to convince Americans and the world about the need for action.
So far, he is finding few international partners willing to engage in a conflict that has claimed more than 100,000 lives in the past 2 1/2 years and dragged in terrorist groups on both sides of the battlefield.
Only France is firmly on board among the major military powers. Britain's Parliament rejected the use of force in a vote last week.
Russia's foreign minister, Sergey Lavrov, said Monday the information the U.S. showed Moscow to prove the Syrian regime was behind the chemical attack was "absolutely unconvincing."
With Navy ships on standby in the eastern Mediterranean ready to launch missiles, Congress on Sunday began a series of meetings that are expected to continue over the next several days in preparation for a vote once lawmakers return from summer break, which is scheduled to end Sept. 9.
Senior administration officials gave a two-hour classified briefing to dozens of members of Congress in the Capitol on Sunday.
Lawmakers expressed a range of opinions coming out of the meeting, from outright opposition to strident support for Obama's request for the authorization to use force.
Among Democrats, Rep. Sander Levin of Michigan said he'd approve Obama's request and predicted it would pass. Rep. Elijah Cummings of Maryland said he was concerned the authorization might be "too broad." Rep. Bennie G. Thompson, the senior Democrat on the House Homeland Security Committee, said the administration still has "work to do with respect to shoring up the facts of what happened."
Republican Rep. Cathy McMorris Rodgers of Washington said she was concerned about what Congress was being asked to approve. Sen. Jeff Sessions, R-Ala., said the war resolution needed tightening.
"I don't think Congress is going to accept it as it is," Sessions said.