WASHINGTON — Forty-four former state attorneys general have asked Congress to investigate whether politics at the Justice Department influenced the prosecution of a former Alabama governor, Don Siegelman, on corruption charges.

Siegelman, a Democrat, was convicted last year of bribery and other charges. He began serving a seven-year prison sentence last month.

Democrats have long maintained that his prosecution was politically motivated, and recent allegations that White House officials were steering decisions at the Justice Department have added weight to the claims.

Last month, a GOP lawyer who once worked on the campaign of Governor Riley, a Republican, signed a sworn affidavit saying she overheard conversations among campaign officials in 2002 suggesting that the White House was involved in Siegelman’s prosecution. She has offered to testify to any investigative agency or in court.

“The only way to convince the public that the governor is not the victim of a politically motivated double-standard is for Congress to investigate all aspects of the case thoroughly,” the former attorneys general wrote to the chairmen of the House and Senate judiciary committees.

The group includes Democrats and Republicans and is led by Jeff Modisett, an Indiana Democrat; Bob Abrams, a New York Democrat; Bob Stefan, a Kansas Republican, and Grant Woods, an Arizona Republican.

Congressional Democrats already are investigating whether the White House ordered the firings of several federal prosecutors for political reasons.