PORTLAND (AP) – Democratic Reps. Tom Allen of Maine and Henry Waxman of California traded accusations with Republican Sen. Susan Collins on Thursday over contractor fraud as Iraq once again figured into the Senate race between Allen and Collins.

The two Democrats accused Collins of failing when she served as chairwoman of the Senate Committee on Homeland Security and Governmental Affairs to do anything about $23 billion in contractor waste, abuse and fraud in Iraq. The chairman is now Sen. Joseph Lieberman.

“Senator Collins was absent without leave as chairman of that committee … in pursuing her job to make sure the taxpayers were not being taken to the cleaners by war profiteering,” said Waxman, chairman of the House Oversight and Government Reform Committee.

But a spokesman for Collins says she did hold a hearing on contractor abuse, and that her efforts helped to prevent the elimination of an independent auditor overseeing reconstruction contracts who briefed her committee 12 times. She also sponsored a bill that would address contractor fraud that the Senate unanimously passed.

“It’s no surprise that Congressman Allen’s campaign is continuing to bring up this tired old partisan attack,” said Kevin Kelley, a spokesman for Collins. “The truth is, under Senator Collins’ leadership, she has a record of extremely aggressive and effective oversight.”

Waxman and Collins are at odds over competing versions of bill addressing contractor fraud, but there’s a stalemate in conference committee. Collins’ campaign accused Waxman and Democrats of holding up the Senate bill in conference committee.

Allen and Sen. Frank Lautenberg raised the same issue of contractor abuses earlier this year during a visit to Maine by the New Jersey Democrat.