If you’ve been worn down by too much bad news into thinking that nothing good can ever happen in Washington, here’s proof that it ain’t so: “the biggest ever pro-Iran diplomacy letter from the Hill.”

JTA, the international news agency, reports:

Days after Israeli Prime Minister Benjamin Netanyahu dismissed the incoming Iranian president’s plea for engagement with the United States and called for ratcheting up military pressure, a bipartisan letter circulating in the US House of Representatives is urging President Obama to test Hassan Rohani’s offer. The letter, spearheaded by Reps. Charlie Dent (R-Pennsylvania) and David Price (D-North Carolina), had garnered 118 signatures by Thursday afternoon, more than a quarter of the House. The bulk of the signatories are Democrats, but 15 Republicans have signed on as well.

With 200 Democrats in the House, that means that the majority of House Democrats signed the letter.

And while 15 Republicans is a small group compared to the House Republican caucus, the signature of these 15 Republicans is a big deal. There’s a widespread perception in Washington that “always more war” is the official line of the Republican Party leadership, even though the record shows that on issue after issue – from Afghanistan to Syria – this doesn’t represent the views of rank-and-file Republicans at all. That perception raises the bar for Republicans to publicly speak out for diplomacy. So these 15 Republicans deserve special praise. They’re surely speaking for other Republicans who aren’t yet willing or able to publicly challenge the perceived “always-more-war” party line.

President Obama expressed cautious optimism following Rouhani’s election, telling PBS that he wants “a more serious, substantive” engagement with Iran.

But to seriously test Rouhani’s offer of engagement, Obama needs a little room from Congress. He can’t seriously engage Iran if it’s widely perceived that the whole Congress is working to undermine him. We can be sure that some members of Congress will do everything in their power to try to disrupt and sabotage any possibility of diplomatic progress with Iran, as part of their long game to ensnare the United States in another Middle East war. To counteract that, we need other members of Congress – especially Republicans – to speak up and say: “The ‘always-more-war’ people don’t speak for me. I want the president to test whether there is a chance for a diplomatic solution.”

Earlier this week, a bipartisan group of former US officials wrote to President Obama, calling the election of Rouhani “a major potential opportunity to reinvigorate diplomatic efforts to resolve the standoff over Iran’s nuclear program” and strongly encouraging him to “seize the moment to pursue new multilateral and bilateral negotiations with Iran once Rouhani takes office and to avoid any provocative action that could narrow the window of opportunity for a more moderate policy” out of Iran.

Writing in The New York Review of Books, William Luers, Thomas Pickering and Jim Walsh call for “active diplomacy” with Iran, noting our repeated and recent national experience that attempts to change other governments through pure coercion have ended in miserable disaster.

There is an opening now for meaningful US diplomacy with Iran that hasn’t existed in many years. President Obama is in his second term. After August 3, Iran will have a new president with an electoral mandate for a more constructive relationship with the United States. Bipartisan fatigue with the endless war in Afghanistan and bipartisan suspicion of military involvement in Syria’s sectarian civil war suggest that magical thinking in Washington about the boundless capacity of military force is at low ebb. There is no guarantee that a sustained US diplomatic effort now will succeed. But we owe it to our troops and to our fellow citizens not to let the “always-more-war” faction sabotage a major diplomatic opportunity before it is tested.