Thirty percent of members of the U.S. House of Representatives have signed a letter calling on President Barack Obama to give peace a chance with Iran's new president, Hassan Rouhani, Whispers has learned.

Rouhani was elected June 14 to lead the country of more than 75 million people, replacing firebrand anti-American leader Mahmoud Ahmadinejad. Rouhani previously served as the country's chief nuclear weapon negotiator and was seen by voters as the less combative option.

"This is the loudest call from Congress for diplomacy with Iran ever," National Iranian American Council Policy Director Jamal Abdi told U.S. News. "This is unprecedented."

Inside Iran, Abdi said, there's hesitation to give ground on nuclear weapons because leaders doubt Congress would cooperate with Obama administration attempts to rescind sanctions.

Iranian President-elect Hasan Rouhani places his hand on his heart as a sign of respect after speaking at a news conference, in Tehran, June 17, 2013. (Ebrahim Noroozi/AP)

The letter expresses support for using "all diplomatic tools" with Iran in exchange for the country abandoning its nuclear weapon ambitions.

"[W]e believe it would be a mistake not to test whether Dr. Rouhani's election represents a real opportunity for progress toward a verifiable, enforceable agreement," the letter says. "In order to test this proposition, it will be prudent for the United States to utilize all diplomatic tools to reinvigorate ongoing nuclear talks."

Although cautiously written, the letter clearly emphasizes the congressmen believe Rouhani's election could transform relations.

"As Iran's former lead nuclear negotiator, he has also publicly expressed the view that obtaining a nuclear weapon would run counter to Iran's strategic interests," the congressmen said. "We are mindful of the limitations of the Iranian presidency within the country's political system, of the fact that previous Iranian presidents elected on platforms of moderation have failed to deliver on promised reforms, and of the mixed signals that Dr. Rouhani himself has sent regarding Iran's nuclear ambitions."

The letter's sponsors are Rep. Charlie Dent, R-Pa., and Rep. David Price, D-N.C. As of Friday afternoon 17 Republicans and 114 Democrats had signed, according to a list provided to U.S. News.

"Rep. Price and I, and all the representatives who signed this letter have done so with our eyes wide open," Dent told U.S. News in an emailed statement. "This letter represents a belief that the Administration should keep all options on the table. Now is the time to test whether Dr. Rohani’s actions will match his rhetoric. That is why we must explore further diplomatic avenues at this critical time."

Republicans who attached their names include New York Reps. Michael Grimm and Richard Hanna, Pennsylvania Reps. Mike Fitzpatrick and Glenn Thompson, as well as North Carolina Reps. Walter Jones and Howard Coble. Rep. Jeff Fortenberry, R-Neb., and Rep. Tom Cole, R-Okla., are among some of the other notable signers.

Many Democrats associated with the Congressional Progressive Caucus, including Rep. Jim Moran of Virginia, also attached their names. Two members of the Democratic House leadership team, Rep. Jim Clyburn of South Carolina, the assistant minority leader, and Rep. Xavier Becerra of California, chairman of the House Democratic Caucus, signed.

"Given the election of a more moderate president in Iran, new opportunities for diplomacy with Iran have emerged," said Jim Lewis, spokesman for the Center for Arms Control and Non-Proliferation. "Here, members of Congress are taking pro-active action to encourage the president to seek a diplomatic solution to a decades-old problem."