Relatives of two young men who were lured away by Islamic radicals plan to tell a House committee Thursday that Muslim leaders in America "brainwashed" and "manipulated" their family members, and that "political fear" is preventing people from talking about Islamic extremism.

The witnesses are part of the panel Rep. Peter King, R-N.Y., plans to call at a controversial hearing on the threat posed by radical Islam in the United States.

King, chairman of the House Homeland Security Committee, has faced persistent and vocal criticism from groups and lawmakers who claim he is unfairly targeting one ethnic group. One Muslim activist on Wednesday said King is "unfit" to lead the committee.

But King has defended his plans and, according to remarks prepared for the hearing, will accuse his detractors of spreading "rage and hysteria." He plans to claim that backing down now "would be a craven surrender to political correctness."

Two witnesses are expected to provide a first-hand account on how their relatives were exploited by Islamic radicals.

Melvin Bledsoe, whose son allegedly attacked an Army recruiting center in Arkansas, said in written testimony -- which Fox News has seen -- that Americans are ignoring the issue.

"There is a big elephant in the room, but our society continues not to see it. This wrong is caused by political correctness. You can even call it political fear," he said.

Bledsoe plans to describe how his son, Carlos, was radicalized when he went off to college in Nashville, Tenn. In his testimony, he explained how his son's personality changed and how, when he returned home for the holidays in 2005, he told his family he converted to Islam. From that point, he changed his name and eventually traveled to Yemen.

"Some Muslim leaders had taken advantage of my son. But he's not the only one being taken advantage of. This is going on in Nashville and in many other cities in America," Bledsoe plans to say. "In Nashville, Carlos was captured by people best described as hunters. He was manipulated and lied to. That's how he made his way to Yemen."

Bledsoe claims his son's link-up with Yemeni extremists was "facilitated by their American counterparts in Nashville. ... Something is wrong with the Muslim leadership in Nashville."

Abdirizak Bihi, whose nephew died in Somalia in 2009 after being recruited out of Minnesota by a Somalian terror group, offers similar criticism.

Bihi, in prepared testimony, said young men in their community were "brainwashed" and recruited to fight for Al Shabab while in the United States. He said the local mosque would not help the families get answers when the young men went missing. Instead, he said, the Muslim leaders turned on the families, accusing them of lying and being used as tools of the "infidels" to damage the mosque.

"Suddenly, in a matter of days, the mosque leadership transformed us from victims of radicalization into pariahs of the community," he said, adding that the leaders urged the families of the missing to stay quiet.

King has attracted some support from other lawmakers, including House Majority Leader Eric Cantor, R-Va., for his decision to hold the hearing. The White House on Sunday also dispatched Denis McDonough, deputy national security adviser, to deliver a speech on Islamic radicalization Sunday at a Virginia mosque. McDonough stressed that the United States does not practice "guilt by association" but also said afterward that the administration welcomes "congressional involvement."

However, other lawmakers and groups have been highly critical.

Senate Majority Leader Harry Reid, D-Nev., slammed King in a statement Wednesday, warning the hearing could divide Americans based on religion.

"I take the threat of terrorism very seriously, and no one is more committed to hunting down terrorists and bringing them to justice, wherever they live, than I am," Reid said. "But I am deeply concerned about these hearings, which demonize law-abiding American Muslims who make important contributions to our society, as I would be about congressional hearings to investigate Catholics, Jews or people of any other faith based solely on their religion."

The Council on American-Islamic Relations joined other groups for a press conference Wednesday denouncing the hearing. CAIR Director Nihad Awad said that King's "bias" and "fear-mongering" make him "unfit" to lead the House committee. Awad condemned violent extremism but said King was spreading "false" allegations and "irresponsible rhetoric" about American Muslims.

CAIR was among the groups that backed a protest in New York City over the weekend.

Dozens of organizations, including the American Civil Liberties Union, also sent out a letter Tuesday comparing King's plans to "McCarthyism and Japanese internment."

But King in his statement plans to urge "responsible" Muslim leaders to reject CAIR and plans to defend his hearing as the "logical response to the repeated and urgent warnings" coming out of the Obama administration.

"There is no equivalency of threat between Al Qaeda and neo-Nazis, environmental extremists or other isolated madmen. Only Al Qaeda and its Islamist affiliates in this country are part of an international threat to our nation," King plans to say.

Fox News' Catherine Herridge contributed to this report.