Hawaii Democratic Rep Tulsi Gabbard, a former Iraq war veteran, told reporters she was undecided and then ticked off remaining questions she had after a two-hour session with top administration officials.
"What are the unintended consequences? What are the outcomes? What are the next moves that could potentially occur that would involve U.S. interests, U.S military, costs - both in human lives, as well as in resources?" Gabbard asked.
A senior administration official told CNN that top officials reached out to more than 125 House members through a variety of conference calls and one-on-one conversations over the past two weeks.
But the "flood the zone" White House approach hasn't prevented a steady list of members from voicing outright opposition or criticism that the case for military action is thin.
The fact that so many members in his own party remain undecided or publicly opposed illustrates that Obama's political capital in Congress is quite low.
California Democratic Rep. Judy Chu participated in a conference call with White House chief of staff Denis McDonough on Wednesday and remains undecided.
While she said there's no question that the al-Assad government used chemical weapons she outlined a laundry list of outstanding questions.
She wants details about contingency plans if Syria retaliates, the lack of international support, reasons why diplomatic efforts can't be explored, and the direct cost to taxpayers.
Chu says her constituents "overwhelmingly ... want me to vote 'no' on this."
She described House Democrats as "war weary. We just came from Iraq and Afghanistan wars. We are war skeptical," Chu said.
Rep Elijah Cummings, a Maryland Democrat who remained undecided, highlighted the stakes for Obama to change minds or persuade Democrats to back him on Syria.
He called it "certainly one of the most important speeches in his career as the president of the United States."