Democrat Alison Lundergan Grimes's campaign has filed suit to prevent Sen. Mitch McConnellAddison (Mitch) Mitchell McConnellCollins: 'Extremely disappointing' ObamaCare fix left out of spending deal House poised to vote on .3T spending bill Budowsky: Stop Trump from firing Mueller MORE's (R-Ky.) campaign and the Kentucky Republican Party from distributing a mailer it says is intended to suppress turnout in Eastern Kentucky.

But McConnell's campaign is now "exploring all legal options" to block a mailer issued by the Kentucky Democratic Party it says is attempting to "sow racial division" in the state with falsehoods.

The official-looking Republican mailer is labeled an "election violation notice" on the outside and warns voters they "are at risk of acting on fraudulent information." It also includes a warning of jail time to anyone who "knowingly and willfully obstructs or retards the passage of the mail."

The inside of the mailer outlines and debunks various attacks from the Grimes campaign, calling them "fraudulent information that is being deliberately spread to voters in your area." A disclosure at the bottom says the mailer is paid for by the Kentucky GOP and authorized by McConnell's campaign.

Grimes campaign manager Jonathan Hurst blasted the mailer as "despicable." 

“Of all the terrible things Mitch McConnell has done during this 30 year career in Washington, this last-ditch campaign he authorized to intimidate Kentuckians and prevent them from exercising their right to vote is unquestionably his most despicable,” he said in a statement.

And the campaign has filed suit in Franklin Circuit Court, seeking an injunction to prevent the McConnell campaign from issuing any further mailers. The campaign's complaint alleges that the mailer is intended to "defame and injure [Grimes] specifically and to further impair her election campaign."

Grimes's campaign says they've received calls from voters in Eastern Kentucky concerned they may be breaking the law if they vote on Tuesday. They pointed to a local report out from Hazard, Ky., revealing the Perry County Clerk has gotten similar calls as further evidence the mailer could have an impact on voters on Election Day.

McConnell's campaign dismissed the controversy over the mailer and pointed instead to a Democratic flyer aimed at African American voters as inappropriate campaigning in the race.

"Alison Grimes spent hundreds of thousand of dollars defaming Senator McConnell and his wife on television with an ad she knowingly aired after it was found to be false and is now attempting to stop the Republican Party of Kentucky from correcting the record," said McConnell spokeswoman Allison Moore.

Moore pointed to a flyer issued by the state Democratic Party that features an African American family and alleges McConnell is "targeting our president and our community" and "leading the effort to take away our right to vote" as the real legal issue in the race.

The only legal question that should be pending in court is the Grimes campaign's reckless attempt to sow racial division among Kentuckians with false information. Their overt targeting of minority voters with false and inflammatory claims in connection with an election must be stopped, and we are exploring all legal options available to do so," Moore said.

Kentucky GOP spokeswoman Kelsey Cooper dismissed the concern from Democrats in a statement obtained by the Courier-Journal.

"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, and went on to call Grimes a part of the "Obama campaign machine."

While McConnell has faced the toughest reelection fight of his career, most recent public polling has shown him holding a slight but steady lead, with a survey out Thursday giving him a five-point lead, just outside the margin of error.

—This piece was updated at 10:15 to reflect comment from McConnell's campaign.