President Obama returned to Washington, having failed to reach an international consensus on attacking Syria and ahead of a critical national address to sell his policy to a skeptical Congress and public.

Obama left the G-20 summit in St. Petersburg, Russia, on Friday with a joint statement signed by 11 attendees condemning Syrian President Bashar Assad for using chemical weapons on civilians and urging an international response.

The signatories, though, were unable to agree on a course of action and nearly half of the countries at the gathering failed to endorse the statement, leaving Obama with little leverage as he seeks to sway lawmakers skittish about committing to another military intervention in the heart of the Middle East.

Obama, who rode into the White House vowing to end the wars in Iraq and Afghanistan, now finds himself trying to convince Congress to endorse new military action without strong international support, making the administration’s pitch to wary lawmakers much harder.

“People are more likely to support military operations if they have the sense that other countries are supportive of it, “Christopher Preble, vice president for defense and foreign policy studies at the libertarian Cato Institute, said of Obama’s challenge on Capitol Hill.

“It’s not words of support or pom-poms over on the sidelines — are other countries actually willing to do something tangible? The answer seems to be no,” he added.

In the Senate, the Foreign Relations Committee approved a measure that would limit any military campaign to 60 days, with a possible 30-day extension for Obama. And that authorization would prohibit the deployment of U.S. ground forces in Syria.

The upper chamber could vote on a use-of-force resolution as early as Wednesday, with passage far from certain.

House lawmakers will attend a private briefing on Monday as the administration provides more evidence on the chemical attack to sway hesitant lawmakers.

Foreign policy aides for Democrats and Republicans in both chambers say that members harbor worries about an extended military engagement and whether an attack would actually lead to further instability in the Middle East.

Obama during a press conference in Russia on Friday sought to allay those concerns.

“I was elected to end wars, not start them,” Obama said, seeking to distinguish Syria from Iraq or Afghanistan.

The president, though, conceded that his task in the days ahead would be a “hard sell,” but is “something I believe in.”

Uncertainty about Congress granting authorization for a Syria strike has also led to questions about whether Obama would act even if lawmakers refuse to back him.

It’s a topic the president doesn’t even want to entertain at this point.

“You’re not getting a direct response,” Obama said dismissively when asked repeatedly by reporters about what he would do if dealt a legislative defeat on Syria.

Deputy National Security Adviser Tony Blinken on Friday, however, told NPR that Obama had no “intention” to move forward on Syria without congressional backing.

The White House downplayed those comments, saying that they were confident Congress would stand with Obama.

Obama’s decision to deliver a national address from the White House underscores the dire political reality for the administration. Failing to convince Congress and the public of his Syria policy could embolden the president’s opponents and hamper other second-term foreign policy initiatives.

Furiously twisting arms behind closed doors, Democratic leaders are trying to deliver a major foreign-policy victory for Obama. But even they are being cautious.

“I think we are going to have 60 votes,” Senate Majority Leader Harry Reid, D-Nev., predicted. But he added: “It’s a work in progress.”

Obama’s Tuesday address to the nation also comes after days of prodding from lawmakers who urged him to directly make his case to the American public. Now the speech could be the president’s last chance to sway the debate before Congress votes.

A spokesman for House Speaker John Boehner, R-Ohio, on Friday, however, suggested that the appeal could come too late to make a difference.