Deputy National Security Adviser Tony Blinken on Friday said President Obama does not intend to strike Syria if Congress rejects his bid to authorize a U.S. military response to the two-year civil war.

“The president of course has the authority to act but it’s neither his desire nor his intention to use that authority absent Congress backing him,” Blinken told NPR on Friday.

The White House, at least publicly, has refused to say what the president would do if he does not win enough congressional support to strike Syria.

After Blinken’s interview, an administration official told the Washington Examiner the White House still expects Congress to approve Obama’s request for military action. And they don’t have an official position on what would happen if lawmakers rebuff the president’s appeal, the source said.

However, signs are emerging that Obama’s inner circle is increasingly wary of going it alone on Syria.

White House aides now view a possible attack against Syria without the backing of lawmakers as “unthinkable,” according to a New York Times report.

Obama has chosen to sidestep lawmakers on issues ranging from immigration to environmental policy. But an authorization of military force would create an even greater constitutional clash and stoke cries from Republicans that Obama is overstepping his executive authority.

The president has not garnered the type of international support for a Syrian strike that the White House had hoped for during the G-20 summit in St. Petersburg, Russia. And on the home front, a growing number of Republicans and Democrats say Obama has failed to effectively make the case for military intervention.