President Barack Obama holds a news conference with Turkish leader Recep Tayyip Erdogan at the White House on May 16, 2013. (Kevin Lamarque/Reuters)President Barack Obama said on Thursday he reserves the right to step up American military and diplomatic efforts to push out Syria’s Bashar Assad, but warned he has “no magic formula” to end that country’s civil war. Speaking at a joint press conference in the White House Rose Garden with Turkish Prime Minister Recep Tayyip Erdogan, Obama also played down the prospects of unilateral U.S. action.

“There are a whole range of options that the United States is already engaged in, and I preserve the options of taking additional steps—both diplomatic and military,” Obama said.

But “there’s no magic formula for dealing with an extraordinarily violent and difficult situation like Syria’s,” he continued. “If there was, I think the prime minister and I would have already acted on it and it would already be finished.”

Obama is under pressure from Congress to escalate America’s role in Syria, where fighting has claimed an estimated 70,000 lives. Sens. Robert Menendez and Bob Corker, the top Democrat and Republican, respectively, on the Senate Foreign Relations Committee, introduced legislation on Wednesday encouraging the White House to arm rebels fighting to topple Assad.

The pressure has increased ever since the White House disclosed that U.S. intelligence had evidence that Assad used chemical weapons, apparently crossing a “red line” Obama set last year. But the president has taken a cautious approach to ramping up America’s participation. On Thursday, he said that "the sooner the better" when it comes to Assad losing power—while playing down prospects for unilateral American action.