WASHINGTON (AP) -- Three Wisconsin congressmen are calling on state and federal authorities in Wisconsin to investigate the activities of a nonprofit group alleged of voter fraud in several other states.

Repbulican congressmen Jim Sensenbrenner, Tom Petri and Paul Ryan sent letters Tuesday to Wisconsin Attorney General J.B. Van Hollen and the state's two U.S. Attorneys to look into the Association of Community Organizations for Reform Now, known as ACORN.

ACORN says it has registered 1.3 million young people, minorities and poor and working-class voters nationwide.

But some of those registration cards have become the focus of fraud investigations in Nevada, Connecticut, Missouri and at least five other states.

State Republicans have been raising fears about rampant voter fraud in Wisconsin for years.