The growing support on Capitol Hill comes as President Obama prepares to fly to Russia, a key Syrian ally.
"I'm leaving my options open," said U.S. Rep. Mike Quigley. "This is an extraordinarily complicated issue. There are a lot of questions to be asked."
Though a number of Chicago-area lawmakers remain non-committal, Republican Congressman Adam Kinzinger from the southwest suburbs joined his party's leaders in the house in supporting the president's plan for military action in Syria.
"This is not about politics," Kinzinger said. "This isn't about whether you voted for the president or whether you didn't vote for the president. This is about America being taken seriously around the globe."
Tuesday, Illinois United States Senator Dick Durbin grilled White House officials.
"What is your assessment of their potential when it comes to the delivery and their capacity when it comes to the amount of chemical agents they have available?" he said.
The White House has mounted an intense lobbying campaign in recent days, warning lawmakers of the risks of inaction in the wake of an alleged chemical weapons attack on civilians by Syrian leader Bashar Al-Assad.
"There's never been a time when a president has gone to Congress and asked for military action and hasn't gotten it. So that would play, I think, very heavily on their minds," said ABC7 political analyst Laura Washington.
Chicago attorney Yaser Tabbara is in Washington lobbying for Syrian opposition forces.
"The opposition's No. 1 priority is to end the bloodshed and to basically take away the abilities of Bashar al-Assad, from ballistic missiles to air force to chemical weapons," Tabbara said.
The signs of growing support on Capitol Hill come as President Obama seeks to bolster international support at the G-20 Summit.
It's being held in Russia, an ally of Syria, and will be attended by Russian leader Vladimir Putin, whose blocked U.S. efforts to punish Syria.
"Both sides have indicated, both Putin and Obama have indicated, that this should obviously be discussed, whether directly between them or simply between their advisors, depends on how frosty things are," said DePaul University professor Tom Mockaitis.
Observers say it is critical for the president to shore up support among lawmakers at home before the G-20 Summit.