Incensed by the election of the first black US president, right-wing militia groups in the United States are rising again after a decade of decline, according to new research on extremist groups.

Ideologically driven by racism and a virulent anti-government, anti-taxation and anti-immigrant agenda, the homegrown groups that thrived in the 1990s and spurred numerous deadly terrorist attacks are expanding, said the Southern Poverty Law Center (SPLC).

"This is the most significant growth we’ve seen in 10 to 12 years," said a law enforcement official quoted by the SPLC in its special report "The Second Wave: Return of the Militias."

"All it’s lacking is a spark," said the official, adding it is "only a matter of time before you see threats and violence."

Attacks continued in the last decade after the 1995 bombing of a government building in Oklahoma, killing 168 people — the deadliest domestic terrorist attack on US soil. Such violent movements mostly subsided in the 2000s, however, following prosecutions and the election of the highly conservative George W. Bush as president, said the SPLC’s Mark Potok.

A key difference today, the Center said, is that "the federal government — the entity that almost the entire radical right views as its primary enemy — is headed by a black man," tapping into the latent rage of white supremacist culture.

According to SPLC research in February, there has been a 54-percent rise in race-based hate groups in the United States since 2000, from 602 then to 926 in 2008.

Their study Wednesday also draws direct correlations between Barack Obama’s presidency and numerous murders of law-enforcement officials this year.

"One man ‘very upset’ with the election of America’s first black president was building a radioactive ‘dirty bomb’… Another angry at the election and said to be interested in joining a militia killed two sheriff’s deputies in Florida," said Larry Keller at the SPLC.

A key component for the rise of militias is a vibrant world of unsubstantiated yet widely publicized conspiracies.

"The current political environment is awash with seemingly absurd but nonetheless influential conspiracy theories, hyperbolic claims and demonized targets… This creates a milieu where violence is a likely outcome," said the Center, citing longtime analyst of radical right-wing movements Chip Berlet.

The other major factor for militia recruitment and acceptance is their ideology being aped and championed by mainstream media commentators and politicians, the report said.

Commentators on cable news were singled out for airing and promoting conspiracy theories — notably Fox News commentator Glenn Beck, who has described Obama alternatively as a "fascist," a "Nazi" and a "Marxist."

Beck, who has a regular audience of some 2.5 million viewers on his nightly show, has even "re-floated militia conspiracy theories of the 1990s alleging a secret network of government-run concentration camps," said the SPLC.

Earlier this year Texas Governor Rick Perry raised the prospect of his state’s secession; US Congresswoman Michele Bachmann said she feared Obama was planning "reeducation camps for young people."

In April, an internal government report also warned of right-wing extremists exploiting worries spawned by the economic downturn and Obama’s election as recruiting tools, which could lead "to the potential emergence of terrorist groups or lone wolf extremists capable of carrying out violence attacks."

Greater Internet access has also boosted access to bomb-making know-how and the ability to reach a vast audience of like-minded people, said the Department of Homeland Security — later criticized by conservatives and veterans groups for singling out returning soldiers.