With Congress still deeply divided over whether to authorize a military strike against Syria, the Senate on Friday will advance a resolution that would allow the attacks but with strict limits on its time and scope.

The Senate will gavel into session briefly Friday, just long enough for the Foreign Relations Committee to officially submit the resolution it approved Wednesday. The measure limits any action to 60 days, with the option of extending it another 30 days.

The resolution marks a first step toward the full debate and possible vote on Syria next week when Congress returns from its August recess.

Lawmakers on both sides of the aisle have raised concerns about the mission, from its cost to potential consequences for the entire Middle East. About 200 lawmakers have already registered opposition to any military intervention in Syria, leaving passage of the measure sought by President Obama uncertain.

Sen. Joe Manchin, D-W.Va., is the latest Democrat to declare his opposition, announcing Thursday that he would not vote with the president. That will make it more difficult for Senate Democrats to come up with the filibuster-proof 60 votes they need to pass it.

“I believe that a military strike against Syria at this time is the wrong course of action," Manchin said. "I believe that we must exhaust all diplomatic options and have a comprehensive plan for international involvement before we act.”

The Obama administration continued to make the case for military action on Thursday, holding another private briefing with lawmakers at the Capitol to help convince them that the regime of Syrian President Bashar Assad not only possesses chemical weapons, but used them Aug. 21 against his own citizens, killing more than 1,400.

Obama remains personally involved in the lobbying effort even while he's attending the G-20 summit in St. Petersburg, Russia, where his top critic, President Vladamir Putin, suggested that he would intervene to protect Syria if the U.S. launched a military strike. White House aides said Obama found time to call lawmakers back home to ask for their support.

"I'm concerned about unintended consequences," Senate Appropriations Committee Chairwoman Barbara Mikulski, D-Md., said on her way to the briefing Thursday.

Many lawmakers left the briefing still undecided. Others said they heard nothing that changed their minds about the measure.

Conservative Republicans remain decidedly against a strike, saying it would be costly and divert too many resources without doing anything to strengthen U.S. security.

"This is not America's war," said Rep. John Culberson, R-Texas, adding that nearly every constituent call to his office has been in opposition to a military strike.

As of Thursday, it appeared the Senate was poised to vote first on the war resolution, which, if passed, would then go to the Republican-led House, where its fate is even less certain than in the Senate.

With so many House Republicans opposing the measure, Obama will need substantial support from his fellow Democrats to pass the resolution.

"Given that the president has not yet demonstrated why military action is in our best interest, given that the administration will not be constrained to keep boots off the ground, and given that there is no clear end-game, I am against the president’s resolution to go to war in Syria,” Rep. Scott Garrett, R-N.J., said Thursday.

Democrats, while praising the president for seeking their approval for a strike, want to place limitations on military action, as the Senate bill would, according to House Minority Leader Nancy Pelosi, D-Calif. In addition to limiting the scope of the mission, lawmakers also want an explicit commitment not to sent U.S. troops to Syria.

Pelosi said earlier this week she backs a strike, but even her support appears qualified.

"The president needs to continue to make the intelligence case to the American people as to the Assad regime’s responsibility for the attack and why it’s in our national interest to respond to it," Pelosi wrote to party members.

Obama's toughest sell may be to the 43 members of the Congressional Black Caucus.

The group will receive a private briefing on Monday, but few of the typically anti-war lawmakers are showing any enthusiasm for military action.

Rep. Gregory Meeks, D-N.Y., said he has not made up his mind but is hearing from voters in his Rockaway-area district.

"There's a large number of them who say we do not want you to go to war," Meeks said. "I'm trying to gather as much information as I can get so I can make a decision."

Meeks said lawmakers are hesitant to back military action in Syria after what happened a decade ago in Iraq, when then-President George W. Bush insisted that Iraq had weapons of mass destruction, a claim later proven untrue.

"We don't want to make the same mistake as we made before," Meeks said.