– GOP operative Andy Parrish, a former chief of staff to U.S. Rep. Michele Bachmann, is expected to tell an Iowa Senate ­ethics panel that her 2012 presidential campaign made improper payments to its state chairman.

Having maintained a public silence so far, Parrish referred questions Wednesday to his attorney, John Gil­more, who said his client will corroborate allegations from another former Bachmann aide, Peter Waldron.

Waldron, a Florida pastor, claims that the campaign hid payments to Iowa Sen. Kent Sorenson, in violation of Iowa Senate ethics rules that bar members from receiving pay from presidential campaigns.

Until now, Parrish has been identified by the committee only as “Witness A,” Gilmore said.

“The time has come to confirm that ‘Witness A’ is Andy Parrish, and he’ll be providing an affidavit with supporting material that completely supports the representations previously made by Peter Waldron,” Gilmore said.

Sorenson has vehemently denied any wrongdoing, calling the ethics charges “totally baseless, without evidence, and a waste of Iowans’ time and money.” Lawyers for the Bachmann campaign also have denied the allegations.

Waldron’s accusations are also the subject of inquiries by the Federal Election Commission (FEC) and the independent Office of Congressional Ethics. The investigations are part of a growing web of legal problems facing Bachmann, including a lawsuit by former staffer Barbara Heki alleging that Sorenson stole a proprietary e-mail list of Iowa home-school families from her personal computer. Those allegations also are the subject of an ongoing police investigation in Urbandale, Iowa.

Gilmore said Parrish can provide the ethics panel documentary evidence that Sorenson was paid $7,500 a month to work on Bachmann’s campaign, money that was funneled to him indirectly through C&M Strategies, a Colorado-based company controlled by Bachmann fundraiser Guy Short.

Among the sources of the funding, Waldron contends, was Bachmann’s independent political organization, Michele­PAC, also headed by Short. Attorneys for Short have denied the allegations, which also are part of the FEC inquiry.

Sorenson rocked the Bachmann campaign in the waning days of the Iowa caucuses when he left to join the campaign of rival Ron Paul. At the time, Bachmann suggested that Sorenson’s defection was prompted by money.

Parrish’s willingness to go public against his former employer and political mentor is likely to send shock waves through Minnesota GOP circles, where both he and his attorney are well-known figures.

Parrish served as deputy campaign manager of last year’s unsuccessful effort to pass a constitutional amendment prohibiting same-sex marriage. Gilmore is a well-known conservative blogger.

“Andy is taking a bit of a risk,” Gilmore said. “But at the same time, he feels loyal to Peter Waldron. Peter’s been out there doing the best he can.”

Waldron, for his part, said Parrish’s willingness to come forward “reflects impeccable character and a sense of civic duty that is extraordinary.”

Parrish’s decision to go public came hours after the Iowa Senate ethics panel set a 10-day deadline for “Witness A” to step forward publicly with information.

The six-member panel — made up of three Republicans and three Democrats — also directed the Secretary of the Iowa Senate, Michael Marshall, to get an update on the status of the police investigation in the Heki case.

Iowa Sen. Wally Horn, a Democrat who chairs the ethics committee, said the panel felt it needs to move forward to resolve the allegations or dismiss them. Waldron originally filed three complaints against Sorenson with the ethics panel in January. One of them, alleging improper business disclosures, has been dismissed. The other two complaints, alleging hidden payments and misappropriation of the e-mail list, are still pending.

Horn said he hopes to resolve the ethics complaints before the legislature adjourns next month. Meanwhile, two sources close to the Bachmann campaign have told the Star Tribune that congressional ethics investigators have questioned them about allegations that her presidential campaign played an improper role in her 2011 book tour.

Kevin Diaz is a correspondent in the Star Tribune Washington Bureau

Twitter: @StribDiaz