Peter King, the New York lawmaker at the center of the controversial hearing, says not to conduct the probe would be a 'craven surrender to political correctness.' Democrats compare the proceeding to Joseph McCarthy's anti-Communist hearings. Los Angeles County Sheriff Lee Baca stresses the need to build trust between the police and Muslim Americans.In opening his congressional hearing on the "radicalization" of Muslims in the United States, Rep. Peter King on Thursday forcefully pushed back against critics who contend his inquiry demonizes an entire community and threatens national security.

"I remain convinced that these hearings must go forward. And they will," King told a packed hearing room on Capitol Hill. "To back down would be a craven surrender to political correctness and an abdication of what I believe to be the main responsibility of this committee -- to protect America from a terrorist attack.

"Despite what passes for conventional wisdom in certain circles, there is nothing radical or un-American in holding these hearings," said King, who chairs the House Homeland Security Committee.

King, a Republican congressman from New York whose district was heavily affected by the Sept. 11, 2001, attacks, convened the hearing because of what he termed a growing threat of homegrown terrorism among Muslim men in the United States.

"Today, we must be fully aware that homegrown radicalization is part of Al Qaeda's strategy to continue attacking the United States," King said. "Al Qaeda is actively targeting the American Muslim community for recruitment. Today's hearing will address this dangerous trend."

King cited the plots to bomb Times Square and the subways in New York, as well as the shootings in 2009 at Ft. Hood, Texas, among others, as examples.

Democrats, civil-rights groups and some terrorism experts have criticized the hearings, saying they could stigmatize Muslim Americans and increase hostility worldwide between Muslims and the U.S. government.

Rep. Keith Ellison a Muslim, offered emotional and sometimes tearful testimony in objecting to King's efforts.

"This committee's approach to this particular subject is contrary to the best of American values and threatens our security," Ellison said, saying that King was assigning "collective blame to a whole group" and was "stereotyping and scapegoating."

His voice broke as he described the actions of Mohammed Salman Hamdani, a paramedic from New York, who died while responding to the 9/11 attacks.

Rep. Bennie Thompson (D-Miss.), the ranking member of committee, warned that the hearings could increase "fear and mistrust" in the Muslim American community.

"An obligation to be responsible does not equal political correctness," Thompson said.

"In scores of hearings and briefings, members of this committee have been told that Al Qaeda's main recruiting tool is the notion that the powers of the West are aligned against the people of the Middle East," Thompson said. "We cannot give this lie a place to rest. I cannot help but wonder how propaganda about this hearing's focus on the American Muslim community will be used by those who seek to inspire a new generation of suicide bombers."

But King received qualified support from veteran Rep. John Dingell (D-Mich.), whose district has a significant population of Muslim Americans. Dingell said the hearing had "great potential" and could produce "good results."

Calling the majority of Muslims in the country "loyal, decent and honorable Americans," Dingell raised the specter of the infamous Sen. Joseph McCarthy of Wisconsin, who chaired the anti-Communism hearings of the 1940s and 1950s. Dingell called on King to conduct the hearings in a "fair, honorable and thoughtful fashion."

Los Angeles County Sheriff Lee Baca, invited by Democrats to appear at King's hearing, stressed the need for building trust between the police and Muslim Americans and other communities in regions such as Southern California. He was the only member of the law enforcement community scheduled to testify.

"The concept of public trust is the core message of my testimony," Baca said. "Policing requires extraordinary ability to interact with people, particularly in a diverse society."

"America is becoming a society of the world," he said.

Baca warned against a "a false assumption that any particular region or group are more prone to radicalization than others," noting a high number of terror-related plots that did not involve Muslims. He also noted that Muslim Americans had helped foil "seven of the last 10" plots launched by Al Qaeda in the United States.