White House deputy national security adviser Tony Blinken said Friday that if Congress rejects President Obama’s request to authorize a military strike against Syria, it is “neither his desire nor his intention” to carry out the attack alone.

“The president of course has the authority to strike, but its neither his desire nor his intention to use that authority absent Congress backing him,” Blinken told NPR News.

That admission is a significant one, as the White House’s repeated caveats declaring that the president could act without congressional approval led many to believe Obama might carry out a strike against the Assad regime even if he was rebuffed by Congress.

Blinken also told the radio network that the U.S. had exhausted all diplomatic solutions to the crisis in Syria, rejecting arguments made by some — including Sen. Joe Manchin (D-W.Va.) — that the U.S. should try to resolve the situation without military force.

“We have severe sanctions on Syria and the Assad regime — we’ve squeezed and squeezed and squeezed,” Blinken said, adding that the administration has “gone repeatedly to the United Nations Security Council” to add additional pressure.