WASHINGTON — An activist organization on Tuesday defended its voter registration practices amid new allegations of voter fraud and a call from Republican lawmakers to investigate irregularities.

In Ohio, Democrat Barack Obama told reporters that the group's registration problems should not be used by the GOP as an excuse to keep voters from turning out on Election Day.

However, a federal appeals court has ordered Ohio's top elections official to set up a system by Friday to verify the eligibility of new voters.

The full 6th U.S. Circuit Court of Appeals in Cincinnati on Tuesday upheld a lower court ruling that Secretary of State Jennifer Brunner must use other government records to check thousands of new voters for registration fraud.

A three-judge panel of the 6th Circuit had disagreed last week, but the full court's ruling overturns that decision.

Ohio Republicans has sued Brunner, a Democrat. Ohio GOP Chairman Bob Bennett called the ruling a victory for the integrity of the electoral process.

Brunner previously had said there was no way to implement the system with such speed.

The Association of Community Organizations for Reform Now, known as ACORN, has registered 1.3 million young people, minorities and poor and working-class voters, the group says.

Some of those registration cards have become the focus of fraud investigations in Nevada, Connecticut, Missouri and at least five other states. Election officials in Ohio and North Carolina also recently questioned the group's voter forms.

More than 13,000 workers in 21 states recruited less-fortunate voters, who tend to be Democrats.

"The vast, vast majority were dedicated workers," ACORN spokesman Kevin Whelan said at a news conference on Tuesday. "They did something remarkable in bringing all these new voters."

The North Carolina State Board of Elections is reviewing suspect voter forms from at least two counties.

A law enforcement official said ACORN has been on the radar of federal investigators. But the official would not say whether an investigation has been opened, and spoke on condition of anonymity because of the sensitivity of the issue so close to the presidential election.

Whelan said ACORN staffers separate applications with missing or false information and flag them for election officials. All applications, including problematic cards, are handed in because some state laws require it, he said.

Whelan said he did not know how many registration cards had problems but believed it was a small percentage. He was unsure how many workers were fired for purposely turning in duplicates or applications with fake information, he said.