A top environmental adviser to U.S. President Barack Obama has resigned from his job in the midst of what he calls "a vicious smear campaign against me."

Van Jones, an adviser on environmentally friendly "green jobs" with the White House Council on Environmental Quality, has been linked to a group that has questioned whether the U.S. government had a role in the September 11 terrorist attacks.

Recent news reports have claimed that Jones's name was included on a 2004 petition that called for congressional hearings into whether decisions made by high-level government officials may have led to the attacks.

Videotape also surfaced depicting Jones, a former civil rights activist from California who later changed his focus to environmental and energy issues, using crude language to describe Republicans.

"On the eve of historic fights for health care and clean energy, opponents of reform have mounted a vicious smear campaign against me," Jones said in his resignation statement.

"They are using lies and distortions to distract and divide."

According to Jones, he has been "inundated with calls from across the political spectrum urging me to stay and fight."

After the reports surfaced, Jones issued a statement on Thursday apologizing for his past comments, and said the 9-11 petition, "certainly does not reflect my views, now or ever."

On Sunday, White House spokesperson Robert Gibbs said Jones "understood that he was going to get in the way" of Obama's plans.

"What Van Jones decided was that the agenda of this president was bigger than any one individual," Gibbs told ABC's "Meet the Press."

Howard Dean, former head of the Democratic National Committee, told "Fox News Sunday" that he thought Jones "was brought down and I think it's too bad. Washington's a tough place that way, and I think it's a loss for the country."

"All of us campaigning for office have had people throw clipboards in front of our face and ask us to sign. And he learned the hard way you ought not to do that," Dean said. "But I don't think he really thinks the government had anything to do with causing 9/11."

As the controversy grew, Republican members of Congress demanded that Jones resign.

Rep. Mike Pence of Indiana released a statement, saying: "His extremist views and coarse rhetoric have no place in this administration or the public debate."

The White House released a statement announcing the resignation early Sunday morning.

Nancy Sutley, chair of the Council on Environmental Quality, also released a statement early Sunday, accepting Jones's resignation.

"Over the last six months, he had been a strong voice for creating jobs that improve energy efficiency and utilize renewable resources," Sutley said.

"We appreciate his hard work and wish him the best moving forward."

With files from The Associated Press