Joe Lieberman
Joe LiebermanOfficial portrait; courtesy of YU

House Democrats are President Barack Obama's “last line of defense” against congressional opponents of the nuclear deal with Iran, according to The Hill. The website, which specializes in covering Congress, said Saturday that “some lawmakers are speculating that as much as half the House Democratic Caucus might be willing to buck the White House” and vote against the deal.

“If [Republicans] bring before us a resolution that says ‘We hereby approve the deal,’ I think that as many as half the Democrats would vote against it,” Rep. Brad Sherman (D-Calif.), a critic of the Iran deal, was quoted as saying.

While House Republicans are unified in opposing the deal, many key Democrats are wavering, and the White House is mounting a full-court press to get them on board, according to the report.

Top officials have been meeting personally with Democratic lawmakers, and Obama has even brought some of them into the Situation Room to go over classified details, wrote The Hill. What is more, at various points during his journey to Africa, “no fewer than 17 House Democrats will join him on Air Force One — a prime opportunity for him to talk up the Iran accord face-to-face.”

Secretary of State John Kerry, Energy Secretary Ernest Moniz and Treasury Secretary Jack Lew held a closed-door briefing on the deal for the full House Wednesday, which Kerry and Moniz followed up the next day with a closed-door meeting for Democrats only. During that meeting, Democrats brought up concerns that “after 15 years, Iran will be a nuclear threshold power,” Rep. Eliot Engel (D-NY) said.

“In many ways this doesn’t prevent Iran from becoming a nuclear power... it just postpones it,” he added. “That’s my major concern.”

“I’ve got 60 days,” — Engel, who is the top Democrat on the House Foreign Affairs Committee — said when asked about whether he backs the deal. “I’m listening, learning and reading, and I have time to make a decision.”

Rep. Adam Schiff (Calif.) — the top Democrat on the Intelligence Committee — is also reportedly undecided.

Lawmakers see the vote as being one of the most crucial of their careers – and fear that casting the wrong vote may haunt them later.

Meanwhile, Former Sen. Joe Lieberman (I-Conn.) told John Catsimatidis on New York’s AM 970 that the deal could be effectively blocked with the help of Sen. Chuck Schumer (D-NY).

“I think it opens the way for a lot of other Democrats to oppose it as well,” Lieberman said of Schumer. “Chuck is the key.”

“How can you make a deal with somebody who says they want to kill you?” Lieberman asked. “Pretty impossible in my opinion.”