The Iran deal is working as advertised by containing Iran’s nuclear weapons program. That non-proliferation success creates a greater one: it vastly lowers the odds of a U.S. attack on Iran and pacifies relations. That’s what makes the deal anathema to those on both sides who would preserve enmity to gain in domestic political fights.

The deal’s fate may be sealed in the coming weeks. A presidential election Friday in Iran will either re-elect Hassan Rouhani, who pushed for the deal and now defends it, or replace him with a hardliner. The Trump administration recently launched a review of Iran policy and the deal, which could yield a decision to try to undermine the agreement or to truly stay in it.

Under the 2015 deal, officially the Joint Comprehensive Plan of Action, Iran agreed to limit its nuclear program in various ways and allow International Atomic Energy Agency inspections in exchange for relief from some of the sanctions that the United States, the European Union, and the UN Security Council had imposed and the release of frozen funds. The deal leaves in place sanctions on Iran for human rights violations, ballistic missile development, and support for terrorist organizations. The Obama administration also dropped charges against a number of Iranian sanctions violators in exchange for Iran’s release of four American prisoners.

Last fall’s elections put the deal in peril. They matched a Republican Senate majority that had openly tried to undermine the deal’s negotiation with a militaristic president who opposed it as a candidate. Trump made typically contradictory statements about the deal in campaigning but mostly voiced hostility typical of GOP hawks. For example, he told the AIPAC convention, “My number-one priority is to dismantle the disastrous deal with Iran.” Trump’s top foreign policy appointees seemed to share a particular hostility to Iran. Even Secretary of Defense James Mattis, who many saw as a lone voice of foreign policy caution, had notably belligerent views on Iran, even bizarrely suggesting that it had created ISIS, despite Iran’s aide for ISIS’s opponents in Iraq and Syria.

Despite this rhetoric, neither Congress nor the administration has raced to dismantle the deal. Congressional leaders have suggested they expect to abide by it. Senator Bob Corker (R‑Tenn), chairman of the Senate Foreign Relations Committee did join the panel’s ranking member Robert Menendez (D‑NJ) to introduce a bill that would heighten sanctions on Iran for missile development, support for terrorist organizations, and human rights abuses. Though adopting the bill would antagonize Iran and make it more difficult for the United States to hold up its end of the bargain, it would not directly violate its terms.

The Trump administration, thus far, has stuck with the deal, while huffing and puffing. Officials say they’ll honor its terms pending a review run by National Security Advisor General H.R. McMaster, who, notably, isn’t a strident proponent of confrontation with Iran, like his predecessor, General Michael Flynn. The State Department recently certified Iran’s compliance but, in the same press release, proclaimed Iran’s continued support for terrorism. Secretary of State Rex Tillerson knocked the deal for failing “to achieve the objective of a non-nuclear Iran,” seemingly referring to its retention of enrichment facilities. President Trump then claimed that Iran is “not living up to the spirit of the agreement” and called it “terrible.”

These statements are a boon to Iran’s hardliners, who call the deal a capitulation to the United States, which they see as irredeemably hostile. Evidence of that hostility also comes in U.S. policy: the Corker-Menendez bill, Iran’s inclusion in the Trump administration’s legally-fraught travel ban, potentially-heightened U.S. military aid for their rival Saudi Arabia in its brutal bombing campaign in Yemen, and a likely massive arms sale to the Saudis.

Ebrahim Raisi, now the main opponent of Iranian President Hassan Rouhani, says he would abide by the deal, but criticizes its failure to deliver the promised broad economic benefits. In recent debates, Rouhani has defended the deal, suggested he can produce greater economic growth by negotiating further sanctions relief, and even blasted the Iranian Revolutionary Guard for trying to undermine the deal through ballistic missile tests. Hawks on both sides thus unintentionally serve each other’s interests.

The difficulty that U.S. opponents of the deal face is that the case for it grows stronger with time, as the White House review should demonstrate. One reason for that is that the deal clearly aids relatively-reformist forces in Iran. Another is new business openings, which generate political support for the deal on both sides. Boeing, for example, has nearly finalized two agreements with Iranian airlines worth nearly $20 billion and conducive to a lot of U.S. jobs. A third reason is that addressing Iran’s problematic activities is easier with the deal in place.

The deal’s imperfections aren’t a reason to abandon it, and no deal could have made Iran saintly. Probably the most dangerous impulse in U.S. foreign policy is to try to eradicate problems rather than to manage them. Recent U.S. wars have shown that a bad situation can always get worse.

At 10 AM tomorrow, we’ll be discussing these issues at Cato. Journalist Laura Rozen will interview Ambassador Wendy Sherman, the lead U.S. negotiator in the talks that produced the deal. Cato’s Emma Ashford and Georgetown’s Ariane Tabatabai will provide comments.