Joseph Gerth

Alison Lundergan Grimes' U.S. Senate campaign said it has filed suit in Franklin Circuit Court alleging that the Republican Party of Kentucky is trying to suppress voter turnout in Eastern Kentucky, where it sent official-looking mailers that say "Election Violation Notice" on the envelope, and is asking for a criminal investigation into voter intimidation.

"This is clearly a scare tactic, and what they are doing to try to manipulate voters," said Jonathan Hurst, Grimes' campaign manager.

Republican Party of Kentucky spokeswoman Kelsey Cooper dismissed Grimes concerns.

"Alison Lundergan Grimes spent hundreds of thousands of dollars smearing Mitch McConnell and his wife, but she's upset about a mailer that holds her accountable for her blatant falsehoods," she said in a statement, before saying that Grimes is part of the "Obama campaign machine."

The mailer warns, "You are at risk of acting on fraudulent information" that the mailer said is being disseminated to voters. According to the suit, it went to voters in Boyd, Perry and Leslie counties.

Hurst said the Grimes campaign has been receiving phone calls from voters in Eastern Kentucky worried that they will be violating the law if they go to the polls next Tuesday.

On MSNBC's "All in With Chris Hayes," U.S. Rep. John Yarmuth, D-Louisville, called the mailer "despicable" and said that it was "sheer desperation" on the part of Sen. Mitch McConnell, whom Grimes is trying to unseat.

Those who look past the rather ominous warning on the envelope will see that it's filled with claims that Grimes has been untruthful in her television advertising and notes that The Washington Post had said that one ad is "the worst ad of a nasty election year."

In fact, that goes a little beyond what the Post actually said, which is that it was "likely" the worst ad of the year.

"Dear Citizen," the mailer reads, "This document serves as a notification to you, as a resident of Kentucky and a registered voter in the aforementioned Commonwealth, of fraudulent information that is being deliberately spread to voters in your area."

Hurst said the campaign believes the mailer may violate criminal voter suppression law and has asked Kentucky Attorney General Jack Conway to investigate the matter.

Former Attorney General Greg Stumbo, a supporter of Grimes, also sent a letter to Conway asking for an investigation.

Allison Martin, a spokeswoman for Conway, said that office has received numerous complaints about the mailer and that they have been forwarded to the state's voter irregularity task force.

Even though it deals with a federal election, which would typically mean that it would be a federal matter, the Attorney General's office could opt to consider the matter if it believes it to be a case of voter intimidation. Martin said the office does not confirm or deny the existence of what may be ongoing investigations.

Mary Trotman, a spokeswoman for the Federal Bureau of Investigation in Louisville, said in an email, "I can't confirm or deny the existence of an investigation."

The suit asked for a temporary injunction preventing the GOP from sending more of the mailers out.