Congressional leaders have petitioned the Trump administration to investigate a pro-Iran lobbying organization that has long faced accusations of acting as the Islamic Republic's unregistered mouthpiece in America, according to official communications obtained by the Washington Free Beacon.

A group of senators has requested that the Trump administration investigate the National Iranian American Council, or NIAC. The council, a pro-Tehran advocacy group with deep ties to the Iranian regime, played a key role in the Obama administration's pro-Iran "echo chamber," which misled Congress and the American people about the terms of the landmark 2015 nuclear deal.

Senators Tom Cotton (R., Ark.), Ted Cruz (R., Texas), and Mike Braun (R., Ind.) are petitioning the Justice Department to investigate NIAC for potential violations of the Foreign Agents Registration Act, which requires that lobbying groups disclose their activities on behalf of foreign nations.

NIAC, which is registered as a U.S. nonprofit, maintains close ties to senior Iranian government officials and has been the subject of public scrutiny for its efforts to broker meetings between American and Iranian officials.

As the Obama administration sought to ink the nuclear accord with Iran, NIAC acted as a central part of what Obama National Security Council official Ben Rhodes described as the administration's "echo chamber." A network of Obama administration officials and outside organizations disseminated talking points to reporters that bolstered the case for the deal and downplayed Iran's sponsorship of regional terror operations.

In recent weeks, NIAC has distributed information condemning the Trump administration's killing of top Iranian general Qassem Soleimani. Many of these NIAC-sponsored talking points repeated the Iranian regime's own propaganda regarding the strike, prompting the lawmakers to seek an investigation into potential violations by NIAC of U.S. law.

"We write to urge you to review the activities of the National Iranian American Council (NIAC) and its sister organization NIAC Action for potential violations of the Foreign Agents Registration Act (FARA)," the senators wrote to Attorney General William Barr, according to a copy of the letter obtained by the Free Beacon.

"NIAC's innocuous public branding masks troubling behavior," the senators wrote. "NIAC's relationship with the Iranian regime and its role amplifying regime propaganda in the United States have been the subject of discussion in Washington D.C. for years."

Most recently, NIAC has distributed Iranian regime talking points regarding U.S. military action in the region, the lawmakers allege.

"For example, on December 31, NIAC circulated an email memorandum blaming the United States government for Iranian-backed militias' repeated attacks against U.S. forces in Iraq and brazen attempt to storm the U.S. embassy in Baghdad. On January 9, NIAC and NIAC Action staffers tweeted and retweeted conspiracy theories deflecting blame from the Iranian regime for shooting down a Ukrainian civilian airliner, killing 176 individuals," the letter stated. "These disturbing actions are only the latest developments of this nature."

NIAC was ordered to pay more than $180,000 in 2013 to the legal defense fund of Hassan Daioleslam, an Iranian-American writer, following a failed defamation lawsuit. Daioleslam accused NIAC of failing to disclose its clandestine lobbying efforts to undo sanctions on Tehran, the Free Beacon previously reported. The U.S. District Court for the District of Columbia said Parsi's work was "not inconsistent with the idea that he was first and foremost an advocate for the regime."

NIAC also recently arranged a conference call that featured 2020 Democratic presidential contenders Bernie Sanders and Elizabeth Warren, as the Free Beacon reported.

NIAC founder Trita Parsi, who is routinely featured on U.S. news programs, was found to have "arranged meetings between Javad Zarif, Iran's former ambassador to the United Nations and current foreign minister, and members of Congress," according to the letter.

Activities of this nature prompted former FBI associate deputy director Oliver Revell to state that "arranging meetings between members of Congress and Iran's ambassador to the United Nations would in my opinion require that person or entity to register as an agent of a foreign power; in this case it would be Iran."

The GOP senators "are concerned that certain organizations that purport to represent the interests of this community, specifically NIAC, may be conducting lobbying and public relations activities in coordination with or on behalf of the government of the Islamic Republic of Iran."

They asked the "Department of Justice [to] evaluate whether an investigation of NIAC is warranted for potential FARA violations and to ensure transparency regarding foreign attempts to influence the U.S. political process."