The clock is ticking for U.S. senators to make up their minds about striking Syria.

Senate Majority Leader Harry Reid, D-Nevada, called an empty Senate chamber to order Friday, officially kicking off the debate that will end in a vote next week on whether to authorize force against Syria. Reid supports the authorization, but dozens of senators have yet to state their position on attacking Syria in response to Syria's use of chemical weapons.

Sen. Dianne Feinstein, D-California, who chairs the Senate Intelligence Committee, said constituents have been calling her office to say they are opposed to military strikes. Recent poll show that most Americans feel that way.

"I knew this was going to be a heavy lift," President Barack Obama said in reference to getting authorization from Congress.

"Ultimately, you listen to your constituents. But you have to make some decisions about what you believe is right for America."

Senate chaplain Barry Black prayed for guidance during Friday's brief four-minute session.

"We look to you today for wisdom as our lawmakers seek to do what is best for our nation and world," said Black.