The election of relative moderate Hassan Rouhani as Iran’s new president is a silver lining on the cloud that has surrounded U.S.-relations. How the U.S. responds will have serious implications for the future safety and security of Americans and Iranians. The president and Congress must rise to the occasion.

The era of war that we are slowly exiting puts the dangers of failing at diplomacy in stark relief. Some might question the likelihood of going to war with Iran given the nation’s war fatigue and the president’s stated commitment to diplomacy. But if the current window of opportunity doesn’t result in progress, the war drums will get louder. Sen. Lindsey GrahamLindsey Olin GrahamKorean peace talks pose new challenge for Trump GOP sold Americans a bill of goods with tax reform law Republicans divided over legislation protecting Mueller MORE (R-S.C.) recently announced that he plans to introduce a bill authorizing force against Iran, in the face of a huge public backlash against possible military action in Syria. This impatience, and specious claims that the U.S. needs to assert its “credibility,” could mean that pressure will increase on the president to use military force.

Those who advocate a military strike on Iran offer a sanitized version of “surgical strikes.” But U.S.-run war games show that a strike on Iran is likely to result in a full-blown regional war. This means men, women and children losing their homes, livelihoods and lives because the U.S. and Iran could not engage in the demanding yet crucial work of diplomacy.  We must have that possible outcome in mind when we decide how vigorously to pursue a negotiated solution.

Rouhani has already sent some positive signals. In his first news conference after his inauguration, he expressed his willingness to engage in “serious and substantive” talks about the nuclear program. The U.S. response to his overtures will help determine whether Rouhani is able to muster enough Iranian support to follow through. He has condemned the use of chemical weapons in Syria, and he and his foreign minister have engaged in some fascinating “Twitter diplomacy,” sending Rosh Hashana greetings.

So far, the response from Congress has been mixed. An unprecedented 131 members of the House of Representatives signed a letter urging President Obama to reinvigorate diplomacy with Iran, and a similar letter is circulating in the Senate. There is a sense that many politicians recognize the changing political winds.

However, the House also passed another in an interminable string of sanctions bills, adding insult to injury by taking the vote just a few days before Rouhani’s inauguration. In a country that feels the weight of already crippling sanctions, passing more before the new president has had a chance to engage is incredibly counterproductive. The Senate has yet to take up the bill.

Many voters were inspired by President Obama’s powerful defense of his pledge to engage with Iran on the campaign trail. He pointed out the folly of refusing to negotiate, even when he took serious heat from his primary opponents. That’s the leader we need now—someone who will resist the pressure to ramp up threats and sanctions because he knows it will ultimately be the smartest path forward.

If he’s going to be that leader, Obama needs Congress’s backing against the hawks. Members of Congress should speak out strongly for renewed diplomatic engagement and tamp down any provocative actions.  We can’t afford to ignore this opportunity for peaceful reconciliation.

Weiss serves as the rabbi and spiritual leader of Kol HaNeshamah in West Seattle, a progressive Jewish community. Benz, director of Legislative Affairs at Faith Action Network, is an ordained minister of the Evangelical Lutheran Church in America. He served as director of the Lutheran Public Policy Office of Washington.