By Susan Heavey
WASHINGTON (Reuters) - U.S. President Barack Obama does not intend to authorize U.S. military force in Syria if lawmakers vote against his proposal seeking action amid allegations of chemical weapons use by Syrian President Bashar al-Assad, a top aide said on Friday.
"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," deputy national security adviser Tony Blinken told National Public Radio.
The comments come as lawmakers weigh whether to pass a resolution authorizing limited strikes against Syria. U.S. officials allege Assad's government used sarin nerve gas in a deadly attack on its civilians on August 21.
U.S. Secretary of State John Kerry, appearing before lawmakers in both the Senate and the House of Representatives this week, has refused to say what he thought Obama would do if Congress did not agree to act on Syria in response to U.S. allegations of chemical weapons use.
Lawmakers are divided over whether and how to respond, and many are still undecided despite efforts by Obama administration officials to build support, including calls from the president.
The Senate Foreign Relations Committee approved a modified version of Obama's resolution on Wednesday, and the full Senate is likely to begin voting next Wednesday.
The timing of a vote in the House remained unclear. Both chambers must approve the measure for it to pass.
Worried about getting embroiled in Syria's civil war, many U.S. lawmakers have voiced concerns over using military force without backing from the United Nations or a broader coalition of other countries. Some have also said they want the United States to pursue other diplomatic and humanitarian options.
But Blinken cited the severe sanctions imposed on Assad already, and said that the UN has failed to act on even more basic steps.
"At this point, we have unfortunately exhausted everything," he told NPR's "Morning Edition" program.
(Reporting by Susan Cornwell and Susan Heavey)