A Senate ethics panel opened an inquiry into the allegations earlier this year, when a complaint was filed by another former Bachmann aide Peter Waldron.

An Iowa campaign adviser to former Republican presidential candidate Michele Bachmann released an affidavit Monday saying the Minnesota congresswoman approved a plan to indirectly pay an Iowa state senator to work on her 2012 campaign — an arrangement that could violate Iowa Senate ethics rules.

The affidavit from Andy Parrish, who was Bachmann's chief of staff and later served on her Iowa campaign, was posted online Monday. In the document, Parrish states that he recruited Republican Sen. Kent Sorenson, of Milo, to work on the campaign and that "Sorenson indicated to me that he would like to be paid for his efforts supporting the Congresswoman."

State Senate ethics rules prohibit paid employment with political campaigns.

In the affidavit, Parrish says he suggested that a company run by a Bachmann supporter pay Sorenson and that the payment was set at $7,500 a month. Parrish states that Bachmann approved the arrangement and Sorenson had indicated to the campaign that it did not "run afoul of any Iowa Senate ethics rules." Parrish includes emails that show him discussing the plans with campaign staffers and Sorenson.

Sorenson has denied receiving any payments and in a text message said the affidavit was "the same regurgitated garbage that they have been claiming and I stand by my previous comments."

A Senate ethics panel opened an inquiry into the allegations earlier this year, when a complaint was filed by another former Bachmann aide Peter Waldron. The committee is awaiting a printed copy of the affidavit, which Parrish's attorney John Gilmore said would be delivered by Thursday.

The ethics committee could ultimately recommend a punishment up to suspension or expulsion from the Senate.

Bachmann, a conservative House member, entered the race in June 2011 as the darling of the tea party, and went on to win the Iowa GOP presidential straw poll two months later.

But within weeks, staff and senior leadership were abandoning the campaign and key supporters were complaining about its disarray. Bachmann went on to finish a distant sixth-place in the January 2012 caucuses and quit the race the next day.

Sorenson left the Bachmann campaign less than a week before the caucuses and endorsed Ron Paul's presidential bid.

Bachmann also is being investigated by the U.S. House's Office of Congressional Ethics in light of Waldron's complaint. And Bachmann's campaign and Sorenson also are being sued by a former staffer who claims Sorenson stole a private email.

Bachmann's attorney, William McGinley, said in an emailed statement that Bachmann followed "all applicable laws and ethical rules."

"The affidavit by a former employee in fact confirms that Congresswoman Bachmann followed all applicable laws and ethical rules and instructed those working for her to do the same," said McGinley, who is based in Washington, DC. "The alleged arrangement at issue was both lawful and properly reported under federal law. This dispute is between the Iowa Senate and an Iowa Senator: it has nothing whatsoever to do with Congresswoman Bachmann or her political committees. For anyone to suggest otherwise is both dishonest and reprehensible."