An anonymous automated phone call is reaching thousands of registered Democrats in their homes in Kentucky.
"Dan Mongiardo has sold out coal country and the people of eastern Kentucky for campaign cash," the message begins.
The message claims this next track is Mongiardo speaking to an environmentalist group on the cap-and-trade bill.
"The cap and trade bill is a good idea," the message said.
Mongiardo in previous interviews has said he is firmly against cap-and-trade, and denies ever saying this.
"These are illegal and outrageous lies. They are completely anonymous. If there is truth where's the proof," Mongiardo said.
He suspects his chief opponent in the primary, Jack Conway, is responsible.
"He's trying to divide eastern Kentucky. Because he knows if the voters of the area stick together, we'll have a United States Senator from eastern Kentucky," Mongiardo said.
Conway's campaign team denies any involvement in the automated phone call.
"They are absolutely not our calls. Anything said otherwise is a desperate attack from the Mongiardo campaign," Conway spokesperson Allison Haley said.
Both Mongiardo and Conway's campaign say this robocall will not affect their own plans to win the primary.