Facing the most perilous passage of his presidency, Barack Obama is to redouble his efforts to persuade a sceptical US Congress and American public to back strikes against Syria.
The President and his team are using a variety of methods to convince opponents - among them videos of squirming gas victims, an Oval Office address tomorrow and deploying myriad surrogates to speak on his behalf.
The task has in recent days become more daunting. Members of Congress returned to Washington today after mostly being besieged by their constituents to vote against action. Getting an authorising resolution through the Senate looks difficult; prospects of passage by the House worse, with more than 200 members already indicating their opposition. A tally by the Huffington Post website yesterday of House members had 233 either against or leaning "no" with only 39 in favour.
What happens on Capitol Hill in the next days may determine whether missiles aimed at Syria are fired and also shape the legacy of Obama, whose authority, at home and abroad, is surely on the line.
While the President could theoretically ignore a "no" vote in Congress and order strikes anyway, to do so would almost surely elicit an impeachment effort by conservative and Tea Party Republicans.
To his critics, Obama has only himself to blame for the predicament.
"This is an unmitigated disaster. It's amateur hour at the White House," Karl Rove, the former George W. Bush aide, declared. "If he gets the authority it shows that he's not a lame duck," said John Feehery, a former House Republican leadership aide. "If he doesn't get the authority, it's devastating."
Chief of staff Denis McDonough played down the political stakes. "The President is not interested in the politics of this," he said.
Obama will sit down with all the major networks and news cable channels today to make his case before his Oval Office address tomorrow.
The American Israel Public Affairs Committee has plans to swarm Capitol Hill tomorrow with 250 lobbyists to urge members of Congress to support strikes. Israel's Ynet news agency quoted senior Israelis close to Prime Minister Benjamin Netanyahu as saying that in recent days he has spoken with members of Congress and figures in AIPAC to explain to them the importance of an American military strike against the Assad regime.
The White House is recruiting figures of influence from every corner to help to make the case. Hillary Clinton will speak out for strikes at two events this week. David Petraeus, a former general and CIA director, has urged action, as did the former Defence Secretary Robert Gates.
On the CBS network, President Bashar al-Assad surfaced asserting his innocence. "There has been no evidence that I used chemical weapons against my own people," the network reported him claiming in an interview in Damascus.
In a sign that continued talk of military intervention may be having an effect on the Syrian leadership, Charlie Rose, who conducted the interview, said that Assad expressed concern that a US attack might degrade the Syrian military and tip the balance in the civil war.
Secretary of State John Kerry arrived in London as part of a tour of European capitals to stiffen the support of key allies. So far Washington has not seen any point in re-engaging the UN because of Russia's veto or even awaiting the results of the UN inspectors' mission to Syria. But the British ambassador to the UN, Sir Mark Lyall Grant, hinted that debate might yet resume in the Security Council.
The Senate Intelligence Committee yesterday posted 13 videos on the internet that "claim to show victims of a chemical or poison-gas attack", according to the committee's website. The videos, allegedly showing civilians gasping and suffering spasms after exposure to the attacks, were supplied by the Syrian opposition and assembled by the CIA.
"Those videos make it clear to people that these are human beings, children, parents, being affected in ways that are unacceptable," Kerry said. "And the US has always stood with others to say we will not allow this."