A coal executive is threatening to sue Congressman Ben Chandler over a recent campaign ad.

Chandler is facing Republican Andy Barr in the November election. Executive Heath Lovell appeared in a Barr ad recently wearing a hardhat and miner’s garb.

In response, Chandler has been running an ad saying Lovell is not actually a coal miner.

Lovell’s attorneys sent Chandler a letter today asking that the campaign take down the ad. The letter also included certificates to show Lovell is a certified miner for underground and surface coal operations in the commonwealth.

A spokesperson for Chandler did immediately not return a request for comment.