Ron Dermer, Israeli ambassador to the U.S., warned Republicans against the Iran nuclear deal Wednesday in a meeting with about 40 House GOP members.

"[Dermer] didn't make an open appeal," against the deal, Rep. Trent Franks, R-Ariz., said after the meeting. "But, it was clearly obvious that he believes, as I do, that this is the most dangerous foreign policy deal that any president has made in my lifetime."

Dermer appealed to lawmakers as the Obama administration works to convince them to support the deal after a 60-day congressional review period expires in mid-September.

Secretary of State John Kerry and other Cabinet members will hold briefings and appear at hearings this week to discuss the agreement, which lifts sanctions against the Islamic state in exchange for lessening of uranium enrichment and centrifuge usage.

Republicans remain mostly opposed to the deal, while many Democrats are undecided.

House Majority Leader Kevin McCarthy, R-Calif., said Tuesday he believes it is possible Congress could vote to disapprove of the deal with a veto-proof, two-thirds majority.

Dermer's meeting with members was organized by and for the Conservative Opportunity Society, which is chaired by Rep. Steve King, R-Iowa. King said he agreed with McCarthy that it's still possible for Congress to block the deal.

"Right now, it's a bit uphill to get there, but it's doable," King said. "And we must, for the security of Israel, for the security of the United States, for the safety of the world."

King said Dermer's message should be heard by everyone.

"I've never heard a more compelling explanation, not only of the Iranian dynamic as they have pursued nuclear weapons, but as this deal affects that dynamic," he said.