WASHINGTON -- An advocacy group under fire after employees were caught on camera appearing to advise a couple posing as a prostitute and pimp to lie about the woman's profession to get housing help said Wednesday it is ordering an independent investigation.

The group, the Association of Community Organizations for Reform Now, known as ACORN, said it is refusing new admissions into its service programs.

ACORN will work with its advisory council -- which includes prominent supporters of President Barack Obama, such as John Podesta, president of the nonprofit Center for American Progress, and Andrew Stern, president of the Service Employees International Union -- to name an independent auditor and investigator, ACORN chief executive Bertha Lewis said in a written statement.

The investigation will examine all the systems and processes called into question by the video, Lewis said.

The nonprofit group came under fire during last year's presidential campaign for its controversial voter registration drives. Two ACORN workers also were arrested in Columbia a few years ago after they used a phone book to register people to vote without their knowledge.

An organizer said last year that ACORN still had a South Carolina presence, but its Columbia office telephone number and e-mail address listed on the group's Web site were not functioning Wednesday.

The group's current crisis revolves not around voter registration but its community service programs. Lewis said ACORN is not accepting new admissions into those programs and will conduct staff training within the next few days.

She said the steps were being taken in response to "the indefensible action of a handful of our employees."

The moves are among several developments in recent days involving ACORN, a liberal-leaning group that is a popular target for Republicans.

Some Republicans are urging the Justice Department to investigate ACORN. The Senate voted Monday to block the Housing and Urban Development Department from giving grants to ACORN, and the Census Bureau last week severed its ties with the group for the 2010 national head-count.

U.S. Rep. Henry Brown, R-S.C., announced that he has signed onto a bill blocking further ACORN funding. "Te last place taxpayer dollars should be allocated is to an organization known for its blatant misuse of these funds," he said.

A video released Monday was among several that have prompted the firing of at least four ACORN employees in Baltimore and Washington. It was created by James O'Keefe and Hannah Giles and posted on BigGovernment.com, where O'Keefe identifies himself as an activist filmmaker.

In the film, O'Keefe and Giles enter an ACORN office and O'Keefe can be heard stating that "we have a unique life situation" and asking if the pair qualify for housing help.

The ACORN housing coordinator and office administrator apparently urge the couple to lie about the woman's profession, with the housing coordinator suggesting that the woman launder the money.

"We have all been deeply disturbed by what we've seen in some of these videos," Lewis said, adding that the group "will go to whatever lengths necessary to re-establish the public trust."

Asked Wednesday about the controversy, White House press secretary Robert Gibbs said that "obviously the conduct that you see on those tapes is completely unacceptable. The administration takes accountability extremely seriously."

Rep. Gus Bilirakis, R-Fla., said he's asked the Federal Emergency Management Agency to repeal a nearly $1 million grant it awarded to ACORN this month.

FEMA awarded $997,402 to ACORN in New Orleans on Sept. 4 as part of its Fire Prevention and Safety Grants program.

The group plans to use the money to assess fire safety in the homes of low- and moderate-income families and hand out smoke and carbon monoxide detectors and other fire prevention gear, ACORN's Brennan Griffin said.