"Many people now treat Muslims as 'the other' - as something to vilify and to discriminate against," said Daniel Mach of the American Civil Liberties Union.

And, he said, some people have exploited that fear in the media, "for political gain or cheap notoriety." The imam leading the project to build the cultural center, including a prayer room, near the site of the September 11, 2001 attacks said there was a rise of what he called "Islamophobia" and the debate had been radicalized by extremists.

Global media coverage of the issue reached fever pitch this weekend with an obscure Florida pastor threatening to burn copies of the Holy Qur’an on the anniversary of the September 11 attacks. He subsequently dropped the threat.

Alan Cooperman of the Pew Forum on Religion and Public Life said, "Americans' opinions of Muslims became more positive after 9/11 than they were before 9/11." Pew polls from 2001 found 59 percent of Americans had a favorable opinion of Muslim Americans two months after the attacks compared to 45 percent in March of that year, and that the biggest improvement was among conservative Republicans.

Cooperman credited the increase to Bush's outreach to show the Muslim community as a religion of peace.

On Friday, Obama himself credited Bush.

"One of the things that I most admired about President Bush was, after 9/11, him being crystal clear about the fact that we were not at war with Islam," Obama said. "We were at war with terrorists and murderers who had perverted Islam, had stolen its banner to carry out their outrageous acts." Mistrust of Muslims has grown in recent years. A Pew poll released in August found the number of Americans with a favorable view of Islam was 30 percent, down from 41 percent in 2005.

American feelings about Islam are partisan — 54 percent of Republicans have an unfavorable view of Islam compared to 27 percent of Democrats. In November 2001 there was not the same partisan divide of opinions on Islam.

Some believe Obama could convert minds were he to mount the type of public relations campaign which saw Bush attend mosques and talk with Muslim leaders back in 2001.

Up to 7 million Americans are estimated to be Muslim. Having a favorable view of the religion is closely correlated with knowing a Muslim. Experts say American Muslims are well assimilated here, well-educated and fare well economically.

"We are Americans. We are doctors. We are investment bankers. We are taxi drivers. We are store keepers. We are lawyers. We are - we are part of the fabric of America, the New York Imam Rauf said.

"And the way that America today treats its Muslims is being watched by over a billion Muslims worldwide," he said.

The run-up to the hotly contested November US congressional elections is also blamed for heightened tension, with some conservatives using nationalist rhetoric and touting their commitment to Christian principles.

Jamie Chandler, political science professor at Hunter College in New York, said Obama should promote a more positive view of Islam but needed the support of fellow Democrats.

When Obama endorsed the right of Muslims to build at the New York site in August, several senior Democrats including Senate Majority Leader Harry Reid and former Democratic National Committee Chairman Howard Dean, publicly disagreed.

"That creates uncertainty in the public," Chandler said.

Further uncertainty is created by public questioning of Obama's Christian faith. A Pew Research Center poll in August showed nearly 1 in 5 Americans thought he was Muslim, up 11 percent from March.

Conservative talk show radio host Rush Limbaugh refers to the president as Barack Hussein Obama, pointedly using his middle name as if to imply he is Muslim.

When General Colin Powell endorsed Obama's presidential bid in 2008, he said Obama was Christian and posed the question - what difference would it make if he were a Muslim? But others feed the divisions. Republican Newt Gingrich, thought to be mulling a presidential run, recently compared the project for a Muslim cultural center near the September 11 site to planting a Swastika near Jewish monuments.