A former ACORN worker in El Paso claims he was fired four years ago by the community activist group after he complained about voter-registration irregularities to the County Elections Office, the El Paso Times reported.

"I was punished unfairly for being a whistle-blower, because I complained about what I observed at the ACORN office," Daniel Mahar, a bartender and stock-market day trader, told the Times.

The El Paso County Sheriff's Office investigated Mahar's complaint about alleged voter-registration irregularities but dropped the inquiry after local prosecutors turned down the case, the Times reported.

Jose Manuel Escobedo, ACORN's regional organizer in El Paso, told the Times, however, that Mahar was fired after he challenged another employee to a fight.

Escobedo also denied that Mahar talked to him twice about alleged irregularities taking place, including renewing numerous voter registrations for people already registered to vote, the Times reported.

"I would say about 10 percent of the ACORN registrations were (irregular)," Mahar told the paper on Thursday.

ACORN, or the Association of Community Organizations for Reform Now, has registered about 4,500 new voters in El Paso County this year, the Times reported.

Meanwhile, New Mexico Republicans took aim at ACORN Thursday, saying at a news conference that the GOP searched public records for 92 newly registered voters in just one state House district who cast ballots in the June primary election and said registrations on file for 28 of those voters were "highly suspect," the Albuquerque Journal reported this morning.

Some of those "suspect" registrations listed Social Security numbers used by other people, New Mexico Rep. Justine Fox-Young, R-Albuquerque, said at the news conference.

"We really have a bombshell," said Fox-Young, who said the majority of the questionable registrations were handled by ACORN.

"It doesn't sound like it's truth. It sounds like it's supposition," Matthew Henderson, head organizer for ACORN in Albuquerque, told the Journal.

ACORN says it has gathered 80,000 new registrations in New Mexico this year, the Journal reported.

The group has said that it had flagged as many as 3,000 of those registrations as problematic for various reasons and have turned those questionable registrations over to county clerks, the Journal reported.

Also on Thursday, a senior law enforcement official confirmed that the Federal Bureau of Investigation is investigating whether ACORN helped foster voter registration fraud around the nation running up to the 2008 presidential election, according to The Associated Press.

A second senior law enforcement officials told the AP that the FBI was looking at the results of inquiries in several states, including a raid on ACORN's office in Las Vegas, Nev., for any evidence of a coordinated national effort.

But two ACORN spokesmen told the AP on Thursday that the FBI has not contacted the group.

ACORN says it has registered 1.3 million young people, minorities and working-class voters this year, most of whom are registered as Democrats, the AP said.