MINNEAPOLIS — The U.S. Justice Department is investigating possibly illegal coordination between U.S. Rep. Michele Bachmann’s 2012 presidential campaign and a political action committee involving the Minnesota Republican’s husband and other campaign officials.

Federal officials have subpoenaed records from the National Fiscal Conservative Political Action Committee as part of a federal grand jury investigation. The move represents a major escalation in the multiple inquiries of alleged election law violations raised by campaign whistleblower Peter Waldron.

The subpoena was first reported by The New York Times.

Bachmann representatives and the NFC PAC did not immediately respond to the Star Tribune’s requests for comment. Bachmann announced in May she would not seek a fifth congressional term next year.

Both Waldron and former Bachmann aide Andy Parrish have acknowledged that the FBI has contacted them. However, the empaneling of a federal grand jury in Washington, D.C., suggests the federal inquiry goes deeper than previously known.

The latest inquiry comes as the House Ethics Committee is poised to render a decision next week on other alleged Bachmann campaign improprieties, including whether she used her campaign staff to help promote her book.

The grand jury subpoena covers financial transactions that involve a number of top Bachmann campaign officials, including her husband, Marcus Bachmann.

The evidence includes an email to Waldron purportedly from Marcus Bachmann, in which he described a telephone conversation he had with PAC President Bill Hemrick to raise money for a fundraiser. Hemrick reportedly suggested that Bachmann contact GOP donor August Busch, who apparently agreed to give $7,000 “thru the NFC super pac,” the email said.

Waldron replied with a warning that raising money through the super PAC could violate federal election laws that prohibit certain types of coordination between campaigns and outside political organizations.

“There are so many rules,” Waldron wrote.

Busch did make a $7,000 contribution to the NFC PAC, according to campaign finance reports.

The email, which is now in the hands of the Justice Department, adds to a body of allegations Waldron made to the Federal Election Commission that prompted investigations by the FBI and the Office of Congressional Ethics.

Waldron’s original FEC complaint alleged that the campaign illegally coordinated with MichelePAC, Bachmann’s own leadership organization.

Waldron and GOP activist John Gilmore recently published an insider e-book critical of Bachmann titled, “Bachmannistan: Behind the Lines.”

Bachmann has denied suggestions that the ongoing ethics probe contributed to her decision not to run for re-election.