Obama says not worried by Muslim "rumors"

President Barack Obama and first lady Michelle Obama cross the street in the Columbia Parc Development to visit newly built homes in New Orleans, Louisiana, August 29, 2010.

WASHINGTON (Reuters) - A public opinion poll showing Americans are increasingly convinced, wrongly, that he is Muslim does not trouble him, President Barack Obama said on Sunday.

"It's not something that I can, I think, spend all my time worrying about it," Obama said in an interview with NBC News, dismissing the results of a recent Pew Research Center.

"I'm not going to be worrying too much about whatever rumors are floating out there. If I spend all my time chasing after that, then I wouldn't get much done."

The Pew poll showed nearly one in five Americans -- 18 percent -- believe Obama is a Muslim, up from 11 percent in March 2009.

In addition, only about one third of Americans surveyed correctly describe Obama as a Christian, a sharp decrease from the 48 percent who said he was a Christian in 2009.

"There is, a mechanism, a network of misinformation that in a new media era can get churned out there constantly," Obama said, on why he thinks Americans appear to be uncertain about his religion.

He said that he dealt with it during his presidential race, and earlier when he campaigned for the U.S. Senate. Obama said he won in Illinois because he trusted the American people's capacity to get beyond the "nonsense."

The Pew survey was completed in early August, before Obama waded into a controversy over a proposed Muslim cultural center and Mosque near the site of the September 11, 2001 attacks in New York.

Proponents of the project met fierce opposition from conservative politicians and those who say it is offensive to families of the nearly 3,000 people killed in the September 11 attacks by al Qaeda militants.

Obama turned what had been mostly a local issue into a national debate when he said he believed Muslim Americans had the same right to practice their religion as other U.S. citizens and supported their right to build the center in lower Manhattan.

In the NBC interview, Obama repeated that religious freedom is a core value of the U.S. Constitution and that it was his job to uphold the Constitution.

"That's something that I feel very strongly about. I respect the feelings on the other side. And I would defend their right to express them just as fiercely," Obama said.

He also said he understood the public anger and frustration expressed by tens of thousands of people in Washington on Saturday at a rally led by Fox TV host Glenn Beck.

"Given all those anxieties, and given the fact that ... in none of these situations are you going to fix things overnight," Obama said, referring to the weak U.S. economy and other problems. "It's not surprising that somebody like a Mr. Beck is able to stir up a certain portion of the country."

(Reporting by JoAnne Allen; editing by Chris Wilson)