WASHINGTON (AP) - President Barack Obama is readying for a high-stakes week of trying to sell a skeptical Congress and a war-weary American public on a military strike against Syria.

The coming days represent one of the most intense periods of outreach for a president not known for investing heavily in consultations with Congress.

Just back from a European trip where he lobbied for support, Obama is working to salvage a policy whose fate he s placed in lawmakers  hands.

His administration s lobbying campaign culminates Tuesday, the evening before a critical vote is expected in the Senate. Obama will address the nation from the White House to make his case for military action.

"Over 1,400 people were gassed. Over 400 of them were children," Obama said Friday at the close of a global summit in Russia.

"This is not something we ve fabricated. This is not something that we are using as an excuse for military action," he said. "I was elected to end wars, and not start them."

A passionate debate in Congress already is underway. Obama enters the fray having made some progress in his quest to win foreign support for a strike punishing Syrian President Bashar Assad for a chemical attack the U.S. blames on his forces.

Yet Obama has been unable to secure the U.N. backing that many nations say is needed to legitimize any strike.

The president returned from Europe with a joint statement from nations backing "a strong international response to this grave violation of the world s rules and conscience."

His administration said the statement, signed by France, Saudi Arabia, Japan and others at the close of the Group of 20 economic summit in St. Petersburg, was a clear endorsement for the limited military action the U.S. has been publicly contemplating for weeks.

Absent from the list was Russian President Vladimir Putin, a stalwart Assad ally and staunch opponent of a U.S. strike.