GARY, Ind.—The Indiana Democratic Party is making a last-ditch effort to save incumbent Democratic senator Joe Donnelly by funding ads and mailers supporting the Libertarian candidate on the ballot in an attempt to split the vote in this heavily conservative state.

As first reported by the Daily Beast, the Indiana Democratic Party on Thursday began purchasing Facebook ads attacking Donnelly's Republican challenger, Mike Braun, as being insufficiently conservative on taxes and government spending. The ads, run through a page created on Oct. 31 called "Hoosier Conservatives," promote Lucy Brenton, the Libertarian candidate, as the "true anti-tax conservative" on the ballot.

Apart from being paid for by the Indiana Democratic Party, the ads are "authorized" by Donnelly's campaign, meaning the senator sanctioned their use.

Around the same time the ads went live on Facebook, Democrats mailed thousands of fliers attacking Braun and boosting Benton to households across Indiana.

"I got two of the mailers last week alone, one on Thursday and the other Saturday," Cyril Herder, a conservative activist, told the Washington Free Beacon.

The mailers, which were sent by the Indiana Democratic Party but not authorized by Donnelly's campaign, accuse Braun of having "raised taxes 159 times" during his three-year tenure in the Indiana House of Representatives, voting for "special tax breaks" for timber and landowners, and supporting Barack Obama and Hillary Clinton. The mailer provides few details to back up its claims.

The ads and mailers further come as polling has shown Donnelly running neck-and-neck with Braun. They seem to be part of a concerted effort by Indiana Democrats to split the GOP's base and ensure Donnelly is reelected.

The Indiana Democratic Party and the Donnelly campaign did not return requests for comment on this story.

Dorn Brenton, the Libertarian candidate's husband and campaign chairman, told the Washington Free Beacon that the Indiana Democratic Party did not seek their approval before undertaking the effort to bolster their campaign.

"We did not know they were going to send out these mailers, we didn't ask for them or the ads," Brenton said. "We certainly don't approve of them."

"This is dirty politics at its best, and we're 100 percent opposed to such tactics, which are often funded by dark money—an issue our campaign has stood up against," Brenton said. "We don't approve and we certainly don't like it. We understand tactically why Democrats are doing [this] but it's still disingenuous."

Even though Democrats have gone to such an extent to split the vote, their ploy doesn't seem to be resonating with voters and may even backfire among its intended audience.

Shannon McNeish, a member of the local United Steel Workers union in Gary, told the Free Beacon he was repelled by the Indiana Democratic Party's attempt to "split the people."

"I got one of those fliers in the mail," McNeish said. "They're trying to split the people, it's dirty and nasty politics, but I guess that's how the Democrats play politics these days. It definitely shouldn't be happening, and I think it's wrong."

The sentiment was echoed by Herder, who told the Free Beacon he had never seen a major party actively "campaign for a Libertarian" and wasn't swayed now.

"The four things they used to criticize Braun on are all things out of the primary campaign that was either shown to be untrue or deceptively taken out of context," Herder said. "It's almost funny."

Herder said he wasn't surprised the Democrats were stooping to such antics.

"It just goes to show how far Democrats and Donnelly will go to protect this seat," he added. "They'll say whatever they need to say for whichever audience in order to win."