The U.S. Chamber of Commerce is up with a new ad in support of Senate Minority Leader Mitch McConnell (R-Ky.) — a sign that it will be behind McConnell as he faces both a tea party primary challenger and a tough general election.

The ad promotes McConnell's opposition to new Environmental Protection Agency regulations against the coal industry.

So far, the chamber has reserved about $177,000 worth of ad time across several markets in early December, according to media-buyer information provided to Post Politics. Politico's Maggie Haberman first reported last week that the ad time had been reserved.

McConnell faces businessman Matt Bevin in the primary and Secretary of State Alison Lundergan Grimes in the general election.

The chamber has signaled an increasing willingness to aid more establishment-friendly GOP candidates against tea party opponents. It recently backed the winning candidate in a special election runoff in an Alabama congressional district.