Peter Baker / New York Times News Service

WASHINGTON — President Barack Obama woke up Monday facing a congressional defeat that many in both parties believed could hobble his presidency. And by the end of the day, he found himself in the odd position of relying on his Russian counterpart, Vladimir Putin, of all people, to bail him out.

The surprise Russian proposal to defuse the American confrontation with Syria made a tenuous situation even more volatile for a president struggling to convince a deeply skeptical public of the need for the United States to respond militarily in yet another Middle Eastern country, this time in retaliation for the use of chemical weapons. It could make the situation even more precarious. Or it could give Obama an escape from a predicament partly of his own making.

In effect, Obama is now caught between trying to work out a deal with Putin, with whom he has been feuding lately, or trying to win over Republicans in the House who have made it their mission to block his agenda. Even if he does not trust Putin, Obama will have to decide whether to treat the Russian proposal seriously or assume it is merely a means of obstructing an American military strike.

“Putin knows that everyone wants an out, so he’s providing one,” said Fiona Hill, a former national intelligence officer and co-author of a book, “Mr. Putin: Operative in the Kremlin.” “It seems like a bold idea that will get everyone, including Obama, out of a bind that they don’t want to be in.”

But, she said, it may be an idea that derails a strike for now without solving the underlying problem. Indeed, the Senate quickly postponed plans for a vote authorizing an attack.

“It just adds to the uncertainty and makes a vote soon a little more difficult,” said Howard Berman, a former Democratic chairman of the House Foreign Affairs Committee. “It just gets dragged out and causes the Congress to say, let’s wait to see what happens with this before they vote.”

All of which had White House speechwriters revising their drafts before Obama addresses the nation tonight in what is shaping up as one of the most challenging moments of his presidency. He hoped to explain why it was necessary to retaliate for a chemical weapons attack that, according to U.S. intelligence, killed more than 1,400 in Syria, but at the same time, reassure Americans the result would not be another Iraq war.

Now Obama needs to also explain why Congress should still vote to authorize such a strike in the face of a possible diplomatic solution and what if any conditions would satisfy him enough to order American destroyers in the eastern Mediterranean Sea to stand down, at least for now. And he has to win over a public that by significant margins opposes U.S. military action.