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.