Federal investigators in North Carolina are seeking an enormous number of voting records from dozens of election offices weeks before the midterm elections, demands that may signal their expanded efforts to prosecute illegal voting by non-U.S. citizens.

The U.S. Attorney’s Office in Raleigh issued subpoenas in recent days on behalf of Immigration and Customs Enforcement to the North Carolina elections board and more than 40 county boards in the eastern third of the state, according to the subpoenas and the state board.

The same federal prosecutor announced two weeks ago that 19 foreign nationals were charged with registering to vote or casting ballots illegally because they weren’t U.S. citizens. More than half were indicted by a grand jury in Wilmington, according to an Aug. 24 news release from U.S. Attorney Bobby Higdon’s office.

The subpoenas direct the information — which the state elections board estimates would cover well over 20 million documents — be provided to a Wilmington grand jury Sept. 25, or before that to a Raleigh-area immigration agent. Higdon’s office had no comment Wednesday, a spokeswoman said. Last month’s news release said the investigation into voting fraud was ongoing.

Still, voting rights activists described the massive document request as a legal fishing expedition. Separately, election officials are worried about trying to meet the deadline while gearing up to administer elections for Congress, legislature and constitutional amendments. Counties could seek deadline delays and the state board plans to discuss its subpoena at a Friday meeting.

Samples of county board subpoenas seek all ballots, poll books and voter authorization forms over the past five years. The subpoena to the State Board of Elections and Ethics Enforcement wants records going back to 2010, including voter registration applications, absentee ballot request forms and provisional balloting forms.

“The subpoenas faxed to county boards are the most exhaustive on record,” state board attorney Josh Lawson wrote Monday to an assistant federal prosecutor who requested last Friday’s subpoenas that have been made public. “Compliance with the subpoena as written will materially affect the ability of county administrators to perform time-critical tasks ahead of absentee voting and early voting.”

Sebastian Kielmanovich, an assistant U.S. attorney who also signed many of the charges announced in August, told Lawson counties could request deadline extensions, according to email correspondence provided by the state board.

Production and printing of ballots already have been delayed this fall in North Carolina by unrelated litigation. Now state officials are working to meet a Sept. 22 deadline in federal law to make absentee ballots available to military and overseas voters.

Kareem Crayton with the Southern Coalition for Social Justice said the subpoenas “raise very troubling questions about the necessity and wisdom of federal interference with the pending statewide elections.”

“With so many well-established threats to our election process from abroad, it is odd to see federal resources directed to this particular concern,” Crayton said in a release.

Greg Flynn, vice chairman of the Wake County elections board, which received a subpoena, said he’s concerned the solemnity of the secret ballot will be threatened should investigators scrutinize absentee ballots. Unlike ballots cast on Election Day, absentee ballots can be linked back to the individual voter.

“The broad scope of this subpoena suggests that they don’t understand how elections work and how elections are managed,” Flynn said in an interview.

It didn’t appear Wednesday the document chase in eastern North Carolina reflected a new uptick in federal scrutiny nationally of voting records and identifying illegal voters. Last month’s cases were brought through a newly created Document and Benefit Fraud Task Force led by Immigrations and Customs Enforcement. Those charged came from Mexico, Nigeria, Japan, Germany, Poland and other countries.