An audit finding that Republican partisanship infected Justice Department hiring has provided fresh ammunition for critics who claim the agency brought charges against Democrats with one eye on the ballot box.

The hiring audit found that Bush officials implemented a screening program in 2002 to weed out job applicants who had liberal or Democratic ties. Such disqualifications, it said, “constituted misconduct and also violated the department’s policies and civil service law that prohibit discrimination in hiring based on political or ideological affiliation.”

“It validates and verifies what we all knew was taking place, and that is that under (the Bush administration) the Justice Department has been politicized and used as a political tool,” former Alabama Gov. Don Siegelman said Wednesday, a day after the report became public.

Siegelman, a Democrat, is fighting to overturn a bribery conviction that he argues was orchestrated by Republican operatives to keep him out of office.

His case is among an unknown number under investigation by the Justice Department’s Office of Professional Responsibility. Among those under scrutiny are prosecutions involving Siegelman, Mississippi Supreme Court Justice Oliver Diaz Jr. and Wisconsin state procurement official Georgia Thompson.

The agency has declined to comment on the investigations, but the fact that it took them up is unusual. According to its most recent annual report, from 2004, OPR opened investigations in just 88 of the 987 complaints it received. Most of those involved isolated instances of misconduct by Justice employees, such as mishandling evidence.

The pending OPR investigation is one of several examining whether the White House influenced Justice Department decision-making. Those accusations were initially driven by the firings of nine U.S. attorneys in late 2006 and culminated with the ouster of Alberto Gonzales as attorney general last September.

Siegelman, once a rising star in Alabama politics, claims that former White House adviser Karl Rove nudged Justice officials in Washington to pursue his bribery prosecution — an allegation backed up by a former GOP campaign volunteer from Alabama.

In Mississippi, critics say Diaz and a prominent Democratic campaign donor were prosecuted on bribery allegations for political reasons.

In Wisconsin, Democrats say Thompson was charged with steering a contract to a campaign donor of Democratic Gov. Jim Doyle in order to damage Doyle’s 2006 re-election bid. Thompson was convicted, but the verdict was overturned, with one judge calling the evidence “beyond thin.”

Federal prosecutors who handled the cases have adamantly denied any undue influence from Washington, saying politics played no role in their decisions. The Justice Department on Wednesday declined to respond to claims that its hiring procedures are evidence of a deeper problem, referring instead to Attorney General Michael Mukasey’s response that politics has no place in such decisions.

“The department’s bald denials that politics never affected the cases under investigation simply cannot be taken at face value,” said House Judiciary Committee Chairman John Conyers, D-Mich.

Stephen Hurley, an attorney representing Thompson, called the audit “unsettling” and said he is eagerly awaiting the next report.

“What they’ve said is politics played a role in personnel decisions. The question is did it play any role in decisions to prosecute,” Hurley said. “The latter is a much more serious issue.”

He and attorneys for Siegelman, however, said OPR has not yet contacted them.

“I’d be glad if somebody called me because I have facts they might want to know,” Hurley said.