A home-building industry group has asked the interim U.S. attorney for Western Washington to investigate possible voter registration fraud in King County.

The issue involves an activist group called Association of Community Organizations for Reform Now, or ACORN, and the nearly 2,000 completed voter registration applications it submitted to the King County elections department in October. A department spokeswoman said in February that the applications appeared suspicious because many of the signatures were similar. Follow-up calls and letters to the supposed registrants have failed to confirm the validity of the applications, she said.

The elections department has so far forwarded 151 apparently fraudulent registrations to the county prosecutor for possible prosecution, and its investigation is continuing, a department spokeswoman said Thursday.

A spokesman for the prosecutor said the records are being reviewed for possible criminal investigation.

County prosecutors said they briefed the U.S. Attorney's Office on the investigation Friday. They did not turn the case over to their federal counterparts and were not asked to, the county prosecutors said.

A lawyer for ACORN wrote the county prosecutor's office March 6 identifying three workers for ACORN's voter registration drive whom he suspected of forging voters' signatures.

A spokesman for ACORN, a national group based in New Orleans, said in February that the organization supported prosecution of anyone involved in fraudulent registration attempts.

The Building Industry Association of Washington asked U.S. Attorney Jeff Sullivan to investigate and prosecute anyone involved in fraudulent registration attempts. The association said it had sent him public records it had obtained, including e-mails among county and state officials discussing the ACORN registrations.

None of the ACORN registrations were submitted in time for the November election. Acting under state law, the elections department recorded the registrations, but flagged them. Any of those registrants attempting to vote would have to provide supporting identification, a state elections official has said.