A super PAC backing Senate Minority Leader Mitch McConnell is again hitting the radio airwaves to tie the Kentucky Republican’s opponent to national Democrats.

Kentuckians for Strong Leadership’s latest ad argues that Kentucky Secretary of State Alison Lundergan Grimes would be an ally to President Barack Obama’s war on coal, an issue likely to be at the forefront for the duration of the race. A previous ad from the group tied Grimes to Senate Majority Leader Harry Reid, D-Nev., on the issue of Obamacare.

A spokesman for the group said it spent $90,000 to air the ad statewide from Wednesday through Dec. 17. Here is the radio ad airing for the next week:

McConnell, the top target of national Democrats this cycle, has been criticized in TV and radio ads by Democratic outside groups. The Grimes campaign has also worked to cut holes in McConnell’s argument that he is coal’s most ardent defender on Capitol Hill.

The race is rated Favored Republican by Rothenberg Political Report/Roll Call.