Six ways the president will try to convince Congress
President Barack Obama has just days to win support from Congress to launch some kind of military strike against Syria. So how is he trying to convince them?
In some eyes, it's not just the future of Syria and the region that rests on two votes being held next week.
The political future of the president also lies in the hands of the 100 senators and 435 members of the House of Representatives he has asked to support him in launching a "limited" attack on targets in Syria.
Many are sceptical that responding in this way to the alleged 21 August chemical weapons attack is in US interests.
So what is President Obama doing to persuade them?
1. Appeal from the heart
From the lawn of the White House, the president made a direct plea not just to Congress but to a deeply divided American nation and to the wider world.
"Ten days ago, the world watched in horror as men, women and children were massacred in Syria in the worst chemical weapons attack of the 21st Century.
"All told, well over 1,000 people were murdered, several hundred of them were children - young girls and boys gassed to death by their own government. This attack is an assault on human dignity."
2. The Oval Office treatment
Senators John McCain and Lindsey Graham swung behind the president after a private meeting at the White House on Monday. They lead the so-called Republican hawks who believe limited strikes are not enough, but their comments when they emerged left little doubt they are now in tow.
On Tuesday it was the turn of House Speaker John Boehner to get a private audience, along with other chairmen and ranking members from the national security committees. Afterwards Republican Boehner, for the first time publicly, gave his support.
Expect more waverers to be given the Oval Office treatment in the days ahead, says Larry Sabato, director of the Center for Politics at the University of Virginia.
"Every moderate Republican who is smart enough to let it be known publicly that he or she is wavering will dangle that in front of the White House."
But how impressed they are by the aura of the office and the glamour of a personal audience depends on who they are, he says.
"If in the moderate, middle group then an Oval Office audience - or lunch or breakfast - might make a difference, because they like to go back and say 'the president really listened to me.'"
3. Let the dogs out
The vote on Syria will be a free vote and the leadership in both Republican and Democratic parties backs Obama, but there's still work for the whips.
"The Democrat whips will be whipping for the president," says Sabato. "The Republican whips will be supplying their leadership with the numbers, because Boehner and Cantor will want more information on who they want to sway.
"They could send certain people [who would vote against a strike] out for coffee during the vote or say, 'take a walk'."
4. Horse trading
There are certain discreet inducements that could be offered to Congressmen and women yet to make up their mind.
These could be Syria-specific, such as an agreement to provide humanitarian help or limit the action to a short time period, says Shaun Bowler, a professor of political science at California Riverside.
Broader rewards could be provided by the mid-term elections in 2014 - a Joe Biden fundraising dinner or help buying television adverts, Bowler adds. "Or perhaps, 'you oppose us now and don't look for help in 2014.'"
Buck McKeon, the Republican chairman of the House armed services committee, said he is "still open" on the issue as he urged the administration to halt cuts in military spending.
5. The president's on the line
A senior administration official has described the strategy in pitching the president's message to Capitol Hill as "flooding the zone" - bombarding members of Congress with calls and briefings.
The overriding message to Democratic waverers will be simple, says Sabato - do not emasculate your president. "The most important thing in one of the most polarised Congresses ever is pure partisan appeal."
President Barack Obama, Vice-President Joe Biden and White House Chief of Staff Denis McDonough all made calls on Sunday to individual lawmakers and again hit the phone lines on Monday.
John Kerry also held a conference call with more than 100 House Democrats and administration officials, to brief them on the intelligence and describe this as America's "Munich moment" - a reference to Prime Minister Neville Chamberlain's appeasement of Hitler in 1938.
6. Get your lieutenants to present the case
Secretary of State John Kerry, Defence Secretary Chuck Hagel and General Martin Dempsey, chairman of the Joint Chiefs of Staff, made the case before the Senate foreign relations committee on Tuesday.
"This is not the time for armchair isolationism," said Kerry. "This is not the time to be spectators to a slaughter. Neither our country nor our conscience can afford the cost of silence."
But the hecklers in the room were a reminder that even if the president wins the vote in Congress, taking the country with him may be beyond him.