WASHINGTON (AP) -- Deep uncertainty surrounding military action against Syria hangs over President Barack Obama's three-day overseas trip to Sweden and Russia, which takes him away from Washington just as he's seeking support on Capitol Hill for a strike.
Before he departed Tuesday night, Obama urged lawmakers meeting with him at the White House to support his plan to punish Syria for allegedly using chemical weapons to attack its own people. The president won the backing of House Speaker John Boehner, R-Ohio, and Democratic Leader Nancy Pelosi of California, though that hardly guarantees support in the fractured House of Representatives.
The president also will seek to bolster international support for a strike during talks with world leaders this week at the Group of 20 summit. Those efforts will pit him against Russian president and summit host Vladimir Putin, who has perhaps done the most to stymie international efforts to oust Syria's Bashar Assad.
Obama and Putin's clashing views on Syria have worsened a relationship already rife with tension from differences on human rights, missile defense, and the Russia's decision to grant asylum to National Security Agency leaker Edward Snowden.
"It's been like watching a slow-moving train wreck for nearly two years," Andrew Kuchins, a Russia expert at the Center for Strategic and International Studies, said of the Obama-Putin relationship. "Mr. Putin and Mr. Obama don't like each other at all. I think there's a deep degree of disrespect."
While Syria isn't officially on the agenda at the economy-focused G-20 summit, the potential for imminent military action is expected to dominate conversations on the sidelines of the summit. World leaders will be seeking guidance from the U.S. president about whether he plans to proceed with a strike if Congress rejects his proposed resolution -- a question Obama's aides have refused to answer.
Votes in the House and the Senate are expected next week, just after Obama wraps up his trip.
During his meeting with lawmakers Tuesday, Obama said he was confident he'll be able to work with Congress to pass a resolution authorizing a strike.
Air Force One left Washington late Tuesday for an overnight flight to Stockholm. The White House hastily added the Sweden visit to Obama's schedule after he scrapped plans to meet one-on-one with Putin in Moscow ahead of the G-20 in response to Russia granting Snowden temporary asylum.
Snowden's leaks to American and foreign news organizations about secret government spying programs have sparked outrage overseas, particularly in Europe. Obama is likely to face questions about the scope of the programs while overseas, as he did earlier this summer during meetings with the Group of 8 industrial nations.
Even before the Snowden incident, relations between the U.S. and Russia were already on the rocks amid differences on missile defense and nuclear weapons, as well as American concerns over human rights and a new Russian law that targets "homosexual propaganda." Russian gay rights activists say they have been invited to meet with Obama while he is in St. Petersburg this week.
Putin also has appeared to relish blocking American and Western European efforts to weaken Assad throughout Syria's 2 1/2-year civil war. Russia remains one of Syria's strongest military and economic backers.
In a pointed jab last week, Putin asked Obama to reconsider a military strike, saying he was appealing to Obama not as a world leader, but as a Nobel Peace laureate.
"We have to remember what has happened in the last decades, how many times the United States has been the initiator of armed conflict in different regions of the world," Putin said. "Did this resolve even one problem?"
Administration officials insist the U.S. and Russia can still work productively together during the G-20, though in a slight to Putin, the White House has gone out of its way to characterize the trip as less of a visit to Russia than a trip to the G-20 that happened to be taking place there.
The White House also has ruled out a one-on-one meeting between Obama and Putin on the sidelines of the summit, though the two leaders certainly will spend time together in the larger summit sessions.
Obama will hold meetings at the summit with French President Francois Hollande and separately with Chinese President Xi Jinping.
Hollande has become an increasingly important ally in the deliberations about military action in Syria. France has indicated a willingness to join the U.S. in a strike, though Hollande said Tuesday that he's waiting for a decision from the U.S. Congress and insisted France won't strike alone.