Congressional ethics investigators are pursuing allegations of financial impropriety in U.S. Rep. Michele Bachmann's 2012 presidential campaign, according to several attorneys and former staffers involved in the case.

The investigation follows a Federal Election Commission (FEC) complaint filed by one of her top campaign lieutenants earlier this year alleging improper payments to a state official in Iowa who is now the subject of a criminal probe in connection with the campaign's use of an email list of Iowa home school families. An attorney for Bachmann's campaign on Monday denied any wrongdoing on her part. But the inquiry by the independent Office of Congressional Ethics (OCE) adds to a mounting list of legal problems stemming from the waning days of her presidential campaign, including an ongoing police investigation and a lawsuit over the email list. A spokesman for Bachmann's congressional office suggested that the disclosure of the new ethics review, though it originates with staffers in her own campaign, was engineered by political adversaries. "Unfortunately, the disclosure of the existence of this review is a predictable and politically motivated attack by Congresswoman Bachmann's political adversaries in an attempt to disparage her reputation as a top-target of the DCCC [Democratic Congressional Campaign Committee] and Democratic Super PACs," said Bachmann spokesman Dan Kotman. "They are willing to do or say anything in an attempt to defeat her in 2014." William McGinley, a Washington attorney representing Bachmann's campaign, said that despite the new inquiry "there are no allegations that the congresswoman engaged in any wrongdoing." McGinley, a top GOP attorney who is also representing Bachmann before the FEC, added, "We are constructively engaged with the OCE and are confident that at the end of their review the OCE board will conclude that Congresswoman Bachmann did not do anything inappropriate." The new ethics probe, first reported in the Daily Beast, could lead to sanctions by the U.S. House, though few of the office's inquiries go that far. The ethics office, established in 2008, looks into charges against House members and their staffs and makes recommendations to the House Ethics Committee. At least three former staffers contacted by the Star Tribune say they have been contacted by the office in the past six weeks, suggesting that the probe has gone beyond the initial 30-day period for a preliminary inquiry. A senior attorney for the ethics office said he could not confirm or deny the Bachmann investigation. Among the board's eight members – half appointed by Democrats and half by Republicans – is former Republican Congressman Bill Frenzel of Minnesota. Frenzel, contacted by the Star Tribune last week, said he could not comment. The OCE, chaired by former CIA Director Porter Goss, was formed in the wake of the Jack Abramoff lobbying scandal to help de-politicize congressional investigations of their own members, which have often been criticized for lacking teeth. The OCE, however, has sometimes been criticized by lawmakers for pursuing questionable complaints.Members of the Congressional Black Caucus once accused the OCE of "targeting" African-Americans after the office investigated then-Rep. Charles Rangel, D-N.Y., over his expenses from a trip to the Caribbean. Although the office received thousands of citizen contacts in the last Congress, formal inquiries can only be launched with the agreement of two board members from different parties. In the past two years, it has begun 32 preliminary inquiries, only 13 of which were transmitted for further review by the House Ethics Committee, according to the board's most recent quarterly report. "We don't chase a lot of wild gooses," said senior OCE attorney Bill Cable. "We find out fairly quickly if there's something there or not." The allegations against Bachmann stem largely from the FEC complaint filed by Peter Waldron, a well-known evangelist who served as the campaign's national field coordinator for outreach to Christian conservatives.Waldron, a controversial figure who once was arrested for possession of assault rifles in Uganda, accused the Bachmann campaign in January of withholding payments to former staffers who refused to sign confidentiality agreements. He also filed papers alleging campaign finance violations involving the campaign and MichelePAC, her independent political action committee. According to his FEC complaint, the campaign improperly used MichelePAC money to pay longtime fundraising consultant Guy Short in the final months leading up to the January 2012 Iowa Caucuses. Waldron also has accused the campaign of concealing payments to Iowa state campaign chairman Kent Sorenson, a state senator who abruptly left the Bachmann camp to join then-U.S. Rep. Ron Paul's insurgent campaign. Short did not return a request for comment Monday. Sorenson's attorney, Ted Sporer, noted that the Iowa Senate has set aside a separate ethics complaint brought by Waldron. "Clearly, we don't think we did anything wrong," Sporer said.Sporer confirmed that the OCE has contacted him in the past month to get a statement from Sorenson. "We're going to be cooperative and truthful," Sporer said. Sporer also denied allegations made in a lawsuit by Barbara Heki, a former Bachmann campaign worker who says Sorenson took an email list of Iowa home-schoolers from her personal computer in the campaign's Urbandale, Iowa, office. Waldron said he spoke to Bachmann and her husband Marcus on three different occasions in late 2011 and early 2012 to raise concerns about the email list and the alleged campaign finance violations. He said he spoke to ethics investigators last month about both sets of allegations, although he believes the new probe is primarily focused on the potential FEC violations. "What she knows and doesn't know, I think is important," Waldron said Monday. "And when she knew." Heki said that she has not been contacted by the ethics office, although one other staffer contacted Monday by the Star Tribune had. Still, Heki believes that her experience raises ethics as well as legal concerns: "By knowingly allowing her campaign to cover up a felony, and let the blame fall on me, Michele committed a much more serious offense that definitely should be scrutinized by both criminal investigators and the House Ethics Committee."