Trita Parsi, founder and president of the National Iranian American Council and an outspoken advocate of engagement with Iran, has never been popular with those that want the U.S. to take a hard line against that country.

But recently, the controversy swirling around his group has reached fever pitch. This month, Rep. Mark Kirk, R-Ill., called NIAC "regime sympathizers," and Parsi became the focal point of a heated online exchange between several prominent magazine columnists and bloggers.

Parsi is philosophical about the controversy, viewing it as a backhanded compliment. "The intensity of the attacks have tended to be tied to the group's level of success and prominence," he said in a phone interview. "The impression [critics] have given is that they're not happy to see another voice gaining prominence" in the debate over Iran.

The son of an Iranian academic who Parsi says was jailed by both the Shah and the ayatollah who overthrew the Shah, Parsi fled with his family to Sweden at the age of four. He came to the United States to attend the Johns Hopkins University's School of Advanced International Studies, where he received a Ph.D.

He founded NIAC in 2002, to give Iranian Americans a voice on their status in this country and on relations with Iran. One of the group's first successes, in 2003, was to reverse Monster.com's automatic excision of any mention of Iran on job seekers' resumes, in what Parsi calls a misguided post 9-11 security measure.

The group has tried to pursue a nuanced approach to Iran's internal affairs: condemning human rights abuses, while urging the U.S. government to engage with the Islamic regime with which the U.S. broke off relations after the 1979 hostage crisis, hard on the heels of the revolution.

Parsi sees the group's advocacy for Iranian Americans at home and dialog with the regime as interrelated. Many Iranian Americans "are concerned about risk of war between countries," he says, not merely because of concern for friends and relations in Iran, but because "discrimination issues would also deteriorate very quickly" in the United States. Parsi also argues that the group's foreign policy stance tracks the views of expressed in polls of Iranian Americans.

Over time, the group has attracted 3,000 paying members -- and a mailing list ten times as large -- who contribute three-quarters of the group's roughly $800,000 budget. The remaining quarter comes from predominantly liberal foundations, including the Rockefeller Foundation, and financier George Soros' Open Society Institute.

Parsi has gained more visibility in recent years, providing frequent commentary on Iran in the media, and since 2007, by hosting an annual conferences on Capitol Hill, whose speakers have included Reps. Jane Harman, D-Calif., and Jim Moran, D-Va. The advent of the Obama administration, which has promised a far less confrontational approach to Iran than its predecessors, has also helped. Parsi was among half a dozen Iran experts invited to a working dinner with Secretary of State Hillary Clinton in September.

But with the increased stature have come more widespread and virulent attacks. Opponents of his views have not only criticized Parsi as wrong-headed, but often sought to paint him as either a sympathizer or agent of the current Iranian regime. Kirk's remarks, for example, were spurred by NIAC's opposition to his measure supporting U.S.-funded democracy programs for Iran, which Pars i-- and some Iranian-based human rights activists -- argued were counterproductive.

The first attacks, Parsi says, came mainly from other Iranian exile factions; but in the past two years, they have been reprised by some conservative and neo-conservative activists. The blogosphere debate began after Parsi teamed up with another target of neo-conservative ire, Jeremy Ben-Ami, the founder of a new liberal Jewish American group called J Street that favors a two-state solution to the Israeli Palestinian conflict. The two coauthored an op-ed after last summer's disputed Iranian elections, arguing against tougher sanctions on Iran and Parsi spoke at J Street's annual conference in late October.

Critics of J Street took aim at Parsi: The Weekly Standard's Michael Goldfarb, called him "the Iranian regime's man in Washington," while the Atlantic's Jeffrey Goldberg said Parsi "did a lot of leg-work for the Iranian regime." But Parsi also attracted defenders, including the Atlantic's Andrew Sullivan and the Center for American Progress' Matt Yglesias -- who essentially called the attacks baseless, politically motivated smears.

Although Parsi sounds philosophical about most of the attacks, he and his group have stepped up their self-defense. They have sued one Iranian exile for defamation -- the case is still pending; and have issued a press release calling on Kirk to retract his "slanderous" remarks. They have also recently hired the PR firm of Brown Lloyd James, and posted an extensive "myths vs. facts" feature on their website, designed to counter allegations made about the group.

Although the NIAC's membership and budget are still growing, Parsi says that he believes the attacks have circumscribed potential growth by "sewing seeds of doubt in community already afraid of politics."