After attending the two-hour briefing, Rep. Ken Calvert, R-Calif., said he is now leaning against authorizing a strike, whereas previously he had been undecided.

“I am more convinced than I was before that President Obama’s strategy is unfocused, unrealistic and unsupportable,” Calvert said. “Tomorrow, I will listen to our House leadership and the president lay out their thoughts on our possible intervention in Syria. Unless I am presented with some new evidence or compelling argument that convinces me that action is in our national security interest, I simply cannot support the use of our American military in Syria as requested by the president.”

Perhaps more troubling for President Obama are the tougher positions of many lawmakers who, until the briefing, had been only leaning against the resolution.

Tonight, Reps. Marsha Blackburn, Charles Boustany, Scott DesJarlais, Tom Graves, Brett Guthrie, Gregg Harper, Sam Johnson, Frank LoBiondo, Blaine Luetkemeyer, Kenny Marchant, Alan Nunnelee and Steve Womack all closed the door on supporting authorization for military force.