The prospect of President Barack Obama winning another four-year term in November is swelling the ranks of anti-Muslim activists and groups on the extremist fringe of American society. Their growth has accelerated every year since Obama took office in 2009.

So says a new report by a civil rights organization, the Southern Poverty Law Center, that has tracked extremist groups for the past three decades and found that last year alone, the number of anti-Muslim groups tripled, from 10 to 30.

Between 2008 and the end of 2011, according to the center, there was an eight-fold increase in the number of militias and “patriot” groups whose members inhabit a parallel universe where the federal government wants to rob them of their guns and their freedom.

“What groups on the radical right have in common is the belief that Obama wants to destroy America,” Mark Potok, author of the report, said in an interview. “Fears that he will win again are now driving the expansion.”

How many Americans are on the right-wing fringe is not known. The Southern Poverty Law Center gives no estimate and neither does the Federal Bureau of Investigation, which also monitors such groups. But it issued a report last September on a sub-set of the far-right scene, “sovereign citizens” who believe that federal, state and local governments operate illegally and therefore have no right to collect taxes. The FBI called them domestic terrorists and “a growing threat.”