WASHINGTON -- President Barack Obama faces a high-stakes week of trying to convince a skeptical Congress and a war-weary American public that they should back him on a military strike against Syria.
His administration came under pressure Saturday from European officials to delay possible action until U.N. inspectors report their findings about an Aug. 21 chemical attack that Obama blames on the Assad government.
Foreign ministers meeting in Lithuania with Secretary of State John Kerry did endorse a "clear and strong response" to an attack they said strongly points to President Bashar Assad's government. Kerry welcomed the "strong statement about the need for accountability." But the EU did not specify what an appropriate response would be.
Obama received an update Saturday afternoon from his chief of staff, Denis McDonough, on the administration's latest outreach to members of Congress, the White House said.
Obama called a bipartisan group of lawmakers on Friday and was expected to make more calls this weekend.
The days ahead represent one of the most intense periods of congressional outreach for Obama, who's not known for investing heavily in consultations with Capitol Hill.
Kerry held talks in Paris with French Foreign Minister Laurent Fabius, and said a joint news conference that "this is not the time to be silent spectators to slaughter" and "this is not the time to allow a dictator unfettered use of some of the heinous weapons on earth."
Fabius said that "punishment is not at odds with a political solution. ... Bashar Assad will not participate in any negotiation as long as he sees himself as invincible."
Just back from a European trip, 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.
Dozens of people opposed to Obama's call for military action demonstrated outside the White House. Speakers chanting "They say more war. We say no war," said the picket line marks a line Congress should not cross as it prepares to vote on the issue.
Obama left the White House during the protest, traveling by car to Andrews Air Force Base to play golf with three aides.
A passionate debate in Congress, which returns to work Monday after its summer break, already is underway.
On Wednesday, the first showdown Senate vote is likely over a resolution authorizing the "limited and specified use" of U.S. armed forces against Syria for no more than 90 days and barring American ground troops from combat. A final vote in the 100-member chamber is expected at week's end.
Democratic Sen. Mark Pryor of Arkansas, running for a third term, said in a statement that "at this time" he can't support action against Syria. Pryor's stance puts him not only at odds with the president, but also Rep. Tom Cotton, his Republican rival in 2014.
A House vote is likely the week of Sept. 16.
A representative from the Syrian National Coalition, spokesman Khalid Saleh, was coming to Washington to meet with government officials and lawmakers.
Obama enters the fray having made some progress in his quest to win foreign support for a strike punishing Assad.
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 contemplating for weeks.
Absent from the list was Russian President Vladimir Putin, a stalwart Assad ally and staunch opponent of a U.S. strike.
European ministers said in their statement Saturday that the available intelligence "seems to indicate strong evidence that the Syrian regime is responsible for these attacks."
But European Union nations want the U.N. investigation to play out and hoped a preliminary report could be released as soon as possible.
But chief U.N. spokesman Martin Nesirky said Saturday that "there will be no preliminary report"
He said the report will go to the Security Council and other member states once the lab analysis is complete. "We are not saying when that will be, except as soon as feasible. This is a scientific timeline, not a political timeline."
The Syrian government denies responsibility, contending rebels were to blame.
The U.S. citing intelligence reports, says sarin gas was used, and that 1,429 people died, including 426 children. The Britain-based Syrian Observatory for Human Rights, which collects information from a network of anti-regime activists, says it has so far only been able to confirm 502 dead.
Obama acknowledged that the U.S. public mostly opposes a strike and that he may not persuade a majority of Americans. But without a forceful response, he said, a fundamental global prohibition against chemical weapons use could unravel, emboldening other leaders with such weapons at their disposal and making the world more dangerous for years to come.
"We are the United States of America. We cannot turn a blind eye to images like the ones we've seen out of Syria," the president said in his weekly radio and Internet address Saturday.
Recent surveys show intense American skepticism about military intervention in Syria, even among those who believe Syria's government used chemical weapons on its people. A Pew Research Center poll completed last week found 29 percent in favor of a U.S. strike, with 48 percent opposed and 23 percent unsure.
The administration's lobbying effort including hosting lawmakers at the White House on Friday for classified briefings on evidence about the attack and on Obama's proposal for a military response.
His new U.N. ambassador, Samantha Power, gave a speech at the Center for American Progress, a Washington think tank with close ties to the White House. Her predecessor at the United Nations, national security adviser Susan Rice, planned to discuss similar themes Monday in an address at the New America Foundation.
McDonough, was preparing to appear on the five major Sunday political talk shows.
McDonough, Kerry, Vice President Joe Biden and Obama were calling lawmakers to urge them to vote yes. On Sunday night, Biden was to host a dinner for a group of Senate Republicans.
Another bipartisan, classified briefing for Congress was scheduled for Monday, and McDonough planned to meet privately Tuesday with the House Democratic Caucus, whose support could be crucial as Obama faces opposition from House Republicans.
House Speaker John Boehner, R-Ohio, and the Democratic leaders in both the House and Senate have backed Obama's call for a Syria strike, but it's unclear how many in either party will join them.