Emily Nordling has never met a Muslim, at least not to her knowledge. But this spring, Nordling, a 19-year-old student from Fort Thomas, Ky., gave herself a new middle name on Facebook.com.

"Emily Hussein Nordling," her entry now reads.

With her decision, she joined a growing band of supporters of Sen. Barack Obama, the presumptive Democratic presidential nominee, who are expressing solidarity with him by informally adopting his middle name.

Obama is a Christian, not a Muslim. Hussein is a family name inherited from his father. But the name has become a political liability. Some critics on cable television talk shows dwell on it, while others, on blogs or in e-mail messages, use it to falsely assert that Obama is a Muslim or, more fantastically, a terrorist.

The movement is hardly a mass one, and it has taken place mostly online. A search revealed hundreds of participants across the country using "Hussein" on Facebook and in blog posts and comments on sites like nytimes.com, dailykos.com and mybarackobama.com, the campaign's networking site.

New Husseins began to crop up online as far back as last fall. But more joined up in February after a conservative radio host, Bill Cunningham, used Obama's middle name three times and disparaged him while introducing Sen. John McCain, the presumptive Republican nominee, at a campaign rally. (McCain repudiated Cunningham's comments). The practice has been proliferating ever since. The new Husseins are embracing the traditionally Muslim name even as the Obama campaign shies away from Muslim associations. Campaign workers ushered two women in head scarves out of a camera's range at a rally this month in Detroit. (The campaign has apologized.) Aides canceled a December appearance on behalf of Obama by Rep. Keith Ellison, a Minnesota Democrat and the first Muslim congressman.

Obama may be more enthusiastic, judging from his response at a Chicago fundraiser two weeks ago. When he saw that Richard Fizdale, a longtime contributor, wore "Hussein" on his name tag, Obama broke into a huge grin, Fizdale said.

"The theory was, we're all Hussein," Obama said to the crowd later, explaining Fizdale's gesture.

Mark Elrod, a political science professor at Harding University in Searcy, Ark., is organizing students and friends to declare their Husseinhood on Facebook on Aug. 4, Obama's birthday.

When Nordling's father saw her new online moniker, he was incredulous.

"He actually thought I was going to convert to Islam," Nordling said.