An embattled Colorado University professor who compared Sept. 11 victims to Nazis struck a defiant tone during a campus speech, saying "I'm not backing up an inch."

Ward Churchill (search), who had filed a lawsuit after officials at the state-funded university threatened to cancel his address, was interrupted several times by applause as he spoke to more than 1,000 people Tuesday night.

Churchill has resigned as chairman of the university's ethnic studies department. Gov. Bill Owens (search) has called for Churchill to be fired, and the university's Board of Regents is investigating whether the tenured professor can be removed.

"I don't answer to Bill Owens. I do not answer to the Board of Regents in the way they think I do. The regents should do their job and let me do mine," Churchill said to thunderous applause. "I'm not backing up an inch. I owe no one an apology."

In an essay, Churchill wrote that workers in the World Trade Center were the equivalent of "little Eichmanns," a reference to Adolf Eichmann (search), who ensured the smooth running of the Nazi system. Churchill also spoke of the "gallant sacrifices" of the "combat teams" that struck America.

The ethnic studies professor said Tuesday his essay was referring to "technocrats" who participate in what he calls repressive American policies around the world.

A longtime American Indian Movement (search) activist, he said he is also culpable because his efforts to change the system haven't succeeded. "I could do more. I'm complicit. I'm not innocent," he said.

The Boulder Faculty Assembly (search), which represents professors at the Boulder campus, has said Churchill's comments were "controversial, offensive and odious" but supports his right to say them based on the principle of academic freedom.

During his 35-minute speech, Churchill said the essay was not referring to children, firefighters, janitors or people passing by the World Trade Center who were killed during the attacks.

The essay and follow-up book attracted little attention until Churchill was invited to speak last month at Hamilton College (search) in Clinton, N.Y., which later canceled his talk out of security concerns.

University of Colorado officials cited those same concerns but backed off after Churchill filed a lawsuit earlier Tuesday asking a judge to force the school to let him speak.

The crowd Tuesday night was loud and orderly as Churchill spoke: "I do not work for the taxpayers of the state of Colorado. I do not work for Bill Owens. I work for you," he said.

About two dozen police officers were scattered inside and around the ballroom where the speech was given. Most of those attending supported Churchill.

"I've read some of Ward's work," said 26-year-old Vinita Laroia, an environmental studies major. "I think what he has to say is true and interesting. I wanted to hear his actual voice say what he's thinking."

The ACLU (search) issued a statement defending Churchill's right to speak out and called on regents, legislators and the governor "to stop threatening Mr. Churchill's job because of the content of his opinions."

David Horowitz (search), a champion of conservative causes who has long accused American universities of overstocking their faculties with leftists, has said firing Churchill would violate his First Amendment rights and set a bad precedent.

He called instead for an inquiry into the university's hiring and promotion procedures to see how Churchill managed to rise to the chairmanship of the school's ethnic studies department.