THEIR first collaboration was informal. In 2008, Mr. Spencer posted Ms. Geller’s appeal to raise $4,000 for a headstone for Aqsa Parvez, a Muslim-Canadian immigrant killed by her father and brother for not wearing a head scarf. More recently, Mr. Spencer worked with Ms. Geller on her book “The Post-American Presidency,” published this summer by Simon & Schuster for what she described as a six-figure advance. He helped her sober up her tone, she said, by removing those “little darlings,” in hopes of bolstering the credibility of her argument that Mr. Obama is “not only presiding over but actively promoting the decline of America.”

The pair populated the 2009 Conservative Political Action Conference with anti-Islam sympathizers by renting a room in the same hotel and hosting a talk by Geert Wilders, the Dutch anti-Islam activist who has tried to ban the Koran in his country. At this year’s conference, they hosted Mr. Gravers, head of Stop Islamization of Europe, whose motto is “Racism is the lowest form of human stupidity, but Islamophobia is the height of common sense.” Mr. Gravers then asked Ms. Geller and Mr. Spencer to take over his group’s American affiliate, and turn it from a staid Web site into a political force.

They delivered. In April, they founded a nonprofit group called American Freedom Defense Initiative, which also uses the name Stop Islamization of America. They took out bus ads offering to help Muslims who wanted to leave the religion but were afraid of violent reprisals — and won in court when cities tried to suppress the ads. They brought crowds to support Rifqa Bary in Ohio and urged people to oppose the mosque on Staten Island.

Then Park51 emerged.

Mr. Spencer and Ms. Geller said they would rather have galvanized the nation with accounts of Muslim girls killed by male relatives over violations of family “honor.” But, Mr. Spencer said, to many Americans the plight of a Muslim immigrant girl is too abstract. “Most people are only concerned with their families and friends and their immediate circle,” he said. “There is a visceral connection that Americans have with 9/11 that is not felt about other issues.”

It is difficult to determine who finances their movement, since their new organization has yet to win tax-free status requiring documentation of donations. Mr. Spencer estimated that since 2009, the two have raised and spent about $150,000 for things like the bus ads and giant television screens for the 9/11 rally, some of it donated through Mr. Spencer’s Jihad Watch, a 501(c)3 nonprofit agency. In recent years, Jihad Watch has been a program of the David Horowitz Freedom Center, which pays him a $132,000 salary and, as Politico.com has reported, has received significant contributions from philanthropists who back the Israeli right.

Asked how much her blog collects in reader donations and advertisements (one promotes a creationist Web site), Ms. Geller said only that it was enough to live on.

She is barreling ahead. Just last week, Atlas called on readers to boycott Campbell’s soup after the company announced that it planned to certify some products as halal — the Muslim equivalent of kosher — with the supervision of a group that Ms. Geller considers a front for terrorists.

“Warhol,” she wrote, “is spinning in his grave.”