Kentucky Lt. Gov. Daniel Mongiardo has an 18-point lead over Jack Conway in the state's Democratic Senate primary, according to a poll for Mongiardo's campaign.

The Garin Hart Yang poll has Mongiardo at 43 and Conway at 25. Nearly 30 percent of voters are undecided, though, and the polling memo notes that Conway has a significant cash advantage heading into the final three months of the campaign.

Mongiardo has shown a lead in most polling of the primary, but his lead in the latest is one of his biggest. Mongiardo's campaign released a poll in May of last year showing a 15-point lead.