Secretary of State John Kerry told a packed meeting of skeptical House lawmakers on Wednesday that a vote against the Iran nuclear deal would be a vote to "go to war," according to members leaving the meeting.

The Obama administration will use the next several weeks to pitch skeptical Republicans and Democrats on the deal before Congress considers voting on the deal. Votes are expected on a resolution to disapprove of the deal.

But despite Kerry's shrill warning about the prospect of armed conflict, some left the meeting saying they weren't convinced. Among the skeptical Democrats was Rep. Dan Lipinski, D-Ill., who said Kerry's approve-or-else pitch was falling flat.

"I think Congress has a role to play here," Lipinski said. "And I don't think that voting 'no' means a vote to go to war. And that is what the argument that seems to be put out there, that a vote of no on this is a vote to go to war. I don't think that's true."

Republicans leaving the meeting said the weren't sold on the plan, even though Kerry worked hard to convince members.

"It's the biggest turnout I've seen for any of these briefings," Rep. John Mica, R-Fla., told the Washington Examiner, after walking out of the meeting. "I don't think they were convincing folks."

"I was perplexed," Tom Rooney, R-Fla. said. "Was this a briefing or was this a sales pitch? There is two sides to every story and clearly that was one side."

Kerry, who was joined by Energy Secretary Ernest Moniz, told lawmakers that the agreement would steer Iran away from a nuclear bomb, an argument that appealed to some Democrats.

"It was very informative," said Rep. Emanuel Cleaver, D-Mo. "The secretary was compelling in everything he said. He was essentially saying, ok, here is the best deal we could get and here is what we got in the deal and I need to know what the alternative is."

But Cleaver, like many other Democrats who attended the meeting, said he remains undecided about whether he'll vote to approve the deal. "I'm reading it, reading everything," he said, motioning to a folder under his arm.

The Obama administration will likely focus its efforts on winning over Democrats, who are needed as a firewall to prevent Congress from overriding a presidential veto if the House and Senate vote down the agreement.