Obama will sit down for interviews with several major news organizations on Monday to make a forceful case in favour of punishing Syrian President Bashar al-Assad with military force for allegedly gassing his own people last month, killing hundreds. The president then addresses the nation in a live televised speech on Tuesday night.
Throughout the weekend, Obama has been personally calling undecided lawmakers from both sides of the aisle to make the case for military action.
He's argued that the U.S. has a moral imperative to respond to Syria as well as a national security responsibility, but hasn't said what his course of action will be if Congress doesn't authorize an attack.
Obama's vice-president, Joe Biden, was also hosting a dinner on Sunday night for as many as a dozen Republican senators, including John McCain, a hawk on Syria.
Yet opposition to a Syrian strike shows no signs of abating, despite the full-court press.
So-called whip counts by various news organizations suggest as many as 229 members in the Republican-controlled House of Representatives are now in the "no" camp, while as few as 44 are likely to opt for a strike in a vote scheduled for Sept. 16. While he might convince the Senate to give him the green light in a vote on Wednesday, Obama needs at least 217 votes in the House to secure his resolution.
Polls also suggest the majority of Americans are opposed to U.S. military intervention in Syria.
White House chief of staff Denis McDonough insisted Sunday it's premature to predict whether the Syria resolution would win approval from Congress. Obama made his surprise decision to seek congressional authorization following a walk with McDonough on the White House grounds 10 days ago.
"We have been working this now for several days while members are in their states and in their districts, so I think it's too early to come to any conclusions," he said on "Fox News Sunday."
The Syrian president undoubtedly "used chemical weapons against his people," McDonough charged, although Assad predictably denied being behind the attacks in an interview Sunday with CBS News set to air as early as Monday.
"So the question now for Congress to resolve this week is: Are there consequences for a dictator who would have used those weapons to gas to death hundreds of children?"
One key liberal Democratic congressman, however, even urged Obama on Sunday to withdraw his request for congressional authoritization for a Syrian strike.
"I don't think the support is there," Jim McGovern, a congressman from Massachusetts, said on CNN's "State of the Union."
"Look, I'm a big supporter of Barack Obama, but sometimes friends can disagree. This is not a question of party loyalty, it's a question of what is right to do."
Indeed, the searing debate has created a bizarre, topsy-turvy spectacle in the U.S. capital over the past two weeks.
To whit: Some Republican lawmakers once gung-ho for an invasion of Iraq are opposing formerly war-wary Democratic senators now clamouring for a strike in Syria. The right-wing Fox News has cited left-wing Think Progress, normally its bitter journalistic enemy, in some of its reporting. Far-right Tea Party adherents are finding themselves in agreement with far-left peaceniks.
Molly Ball, a political writer at The Atlantic, remarked on Twitter: "I thought it was impressive when Obama turned Republicans against golf. But now he's even turned them against war."
Even The Onion, the satirical website that pokes merciless fun at the news of the day, published a headline many pointed to as sadly non-satirical: "Target Of Future Drone Attack Urges American Intervention In Syria."
Intelligence agencies in both the U.S. and abroad have estimated that many of the best-organized rebel fighters in Syria are radical Islamists, some with ties to al-Qaida. A U.S. attack against the Assad regime might strengthen those jihadist forces, undermining secular and pro-Western opposition groups.
"In June, the intelligence showed that of the nine major rebels forces in Syria, at least seven appear to have significant ties to al-Qaida," said Republican Texas Sen. Ted Cruz said on ABC's "This Week."
"And the problem with this strike is one of two things is possible: Either the strike is really significant, it weakens Assad and the result is the rebels are able to succeed, and if what happened there is al-Qaida taking over, or al Nusra taking over, and extremist terrorists getting access to those chemical weapons, that hurts U.S. national security."
With the ghost of the Iraq war still haunting the United States, Americans are now intensely skeptical when elected officials cite intelligence pointing to diabolical misdeeds of Middle Eastern dictators, wary that any conflict in the region can be won anyway and profoundly resistant to the prospect of having to commit American troops to deal with any escalating chaos that might emanate from a strike.
As well, there's no 9-11 driving the argument to act in Syria. A decade ago, the U.S. was still traumatized by the terrorist attacks of Sept. 11, 2001, and many Americans were wrongly convinced Iraq's Saddam Hussein played a role in the carnage.
This time around, the administration is pointing to the heartbreaking images emerging from Syria, in particular videos of civilians — many of them children — gasping for air or near death following the Aug. 21 chemical attack. Those videos were shown last week in a classified briefing to a Senate intelligence committee, and are now being viewed by all lawmakers.
In Paris this weekend, U.S. Secretary of State John Kerry made reference to the footage as he attempted to convince the European Union of the need for military action.
"When you look at those videos of those children heaving for breath, unable to move, spasming, their lives stolen from them, or their parents' lives stolen from them by gas in the middle of the night, when they should have been sleeping comfortably at home in their beds .... are we supposed to walk away from that?"
Note to readers: This is a corrected story. An earlier version said the CBS interview aired Sunday