Vice President JD Vance is the new face of Donald Trump’s Iran deal, as the president returns from his attendance at the G7 summit and remains wary of the intense blowback awaiting him on Capitol Hill.

The vice president took the White House briefing room stand Thursday to discuss the terms of the administration’s 60-day ceasefire extension with Iran, which sets the stage for sanctions relief and immediately triggers processes to allow Iranian oil to hit the global market in what would represent a major economic boon for Tehran and a lifeline for its struggling autocratic government. There is also a $300 billion economic development fund the U.S. hopes to develop with funds sourced from regional investing partners, rather than taxpayer dollars.

Vance’s day in the spotlight was notable as it came just 24 hours after the president jokingly remarked that his vice president would be the fall guy if the administration’s off-ramp to end the four-month war with Iran was poorly received by Congress. That negative reception was playing out on bipartisan lines on the Hill as Vance stepped in to stem the bleeding.

He lashed out at neoconservative critics of the deal within the Trump coalition, who’ve unfavorably compared the memorandum of understanding signed Wednesday to the Obama-era JCPOA, which similarly sought to restrict Iran’s nuclear ambitions.

“The idea that they get benefits before they change their behavior is fundamentally a talking point that is issued by people who want the conflict to continue indefinitely,” Vance told reporters. “No sanctions will come off unless they perform their end of the bargain and every sanction will come back on [if they don’t comply].”

“What I would say to anybody, any of the critics is No. 1, have a little bit of faith in the president of the United States. The idea that he is going to strike a deal that’s bad for the American people, it’s preposterous.”

But on Capitol Hill, the vice president’s assurances were already set to fall on deaf ears. While Republican members of Congress held their fire in terms of criticizing the agreement earlier in the week while the conservative commentariat sphere exploded around them, some of those same senators and representatives are piling on now that the text of the MOU has been released.

One key defection was Mississippi Sen. Roger Wicker, chair of the powerful Senate Armed Services Committee. Wicker’s committee oversees the entire military and is set to be the first stop for a Pentagon supplemental budget request that the Trump administration still hopes to push through Congress this year. He and other hawkish Republicans are deeply concerned about the $300 billion economic development fund, which, along with sanctions relief, they see as aiding a hostile Iranian government in its efforts to cling to power for the foreseeable future.

“The Iranian regime has not renounced its ultimate goal — ‘Death to America, Death to Israel.’ The regime will invest every penny it receives to further that aim,” Wicker warned Thursday.

Wicker is far from alone among Republican, who’ve been reluctant to pick a fight with the White House. Sen. Ted Cruz issued a scathing statement tearing into the president’s closest advisers when asked about the deal by The Independent.

“History demonstrates that sending billions of dollars to theocratic lunatics who want to murder us is a very bad idea, and I think the president is receiving very, very poor advice on this deal. I hope we don’t send a single penny to the Ayatollah,” said the Texas Republican, who sits on the Foreign Relations panel.

Part of Trump’s problems clearly stem from the arm’s length relationship the White House has taken with members of both the Republican House and Senate caucuses this term, often steamrolling GOP priorities on the Hill or complicating the passage of key legislation for Senate Majority Leader John Thune and House Speaker Mike Johnson.

The Senate is currently watching a spying powers provision lapse while the White House issues veto threats over unrelated voter ID legislation and a spat with Democrats over shoving a political operative into the position of director of national intelligence.

To that note, the president’s strongest critic on the signing of the MOU on the Republican side was Louisiana Sen. Bill Cassidy, one of two incumbent GOP senators who lost their respective primaries after Trump endorsed their challengers. Cassidy issued a dismayed statement late Wednesday afternoon, calling the MOU the worst American foreign policy blunder in decades.

“Reagan is rolling over in his grave. Iran’s nuclear ambitions were not curbed, and they have learned that threatening the Strait of Hormuz works and will undoubtedly leverage it in the future. Now, Iran gets to build brand-new infrastructure under this deal,” added the Louisiana senator.

The other Republican senator to face Trump’s electoral shiv this cycle was Sen. John Cornyn of Texas. Cornyn, asked by The Independent about the issue on Thursday, took a more reserved tone. But like Cruz and the others, he seemed opposed to the idea of the economic fund or the unfreezing of Iranian assets in U.S. financial systems.

“It’s still money, and if they get $300 billion they’re gonna.. it’s not going to be for constructive or useful purposes,” Cornyn said.

He also faulted top administration officials for not being on the same page about whether Iran would be allowed to maintain a stockpile of ballistic missiles, noting that Trump’s comments Wednesday clashed with remarks made by Secretary of State Marco Rubio. On Wednesday, Trump posited that Iran should be allowed to stockpile such weapons based on the fact that their neighbors do, telling reporters: “It’s a little bit ​unfair for them not to have some.”

“It’s the opposite of what Marco Rubio said. So they need to sort that out among themselves. I think that’s a bad idea,” said Cornyn.

With Vance making clear that the White House has no plans to submit the MOU to Congress or ask lawmakers for permission to extend sanctions waivers to Iran, it’s clear that the administration recognizes that the gulf between the president and his party’s establishment on the Hill remains very wide. What remains to be seen is whether Thune and other members of the GOP old guard continue to distance themselves from the White House as election season heats up, or whether the president and his team will seek a mending of ties to spur party unity in the face of potential electoral doom.