The U.S. Chamber of Commerce is launching its second TV ad this week highlighting a Republican Senate candidate’s support of the coal industry.

The chamber’s latest spot comes to the defense of West Virginia Rep. Shelley Moore Capito, who is running for an open Senate seat in the Mountain State.

https://www.youtube.com/watch?v=qgImNxKv8eY

As first reported by The Associated Press, the chamber also released TV ads Thursday supporting Rep. Mike Simpson, R-Idaho, who is facing a competitive primary challenge, and GOP state Sen. Evan Jenkins’ challenge to Rep. Nick J. Rahall II, D-W.Va.

The new ads come as the mainstream wing of the GOP fights back against conservative outside groups that play heavily in primaries.

The Senate ad follows a TV ad released on Monday in Kentucky that focused on Senate Minority Leader Mitch McConnell’s efforts to support coal. Coal is poised to play a central role in both states’ Senate races.

The Kentucky ad was backed by a $182,000 airtime buy. The chamber’s independent expenditure filing has not yet been posted by the Federal Election Commission.

Both parties have primaries in the West Virginia race next year, but Capito and Democrat Natalie Tennant, West Virginia’s secretary of State, are favored to win their respective nominations. They are vying for the seat of retiring Democratic Sen. Jay Rockefeller.

“Representative Capito has a record fighting for West Virginians and leading the charge against government overreach, more spending, and job killing regulations,” Rob Engstrom, the chamber’s national political director, said in a statement. “In 2012, she earned a 100% rating with the U.S. Chamber. Our goal is to ensure voters recognize the clear choice they have in 2014 between a leader who stands for free enterprise and those who stand in its way.”

The West Virginia Senate race is rated Leans Republican by Rothenberg Political Report/Roll Call.