The U.S. Chamber of Commerce is backing freshman Rep. David Joyce (R-Ohio) against his Tea Party challenger, Ohio state Rep. Matt Lynch (R).

The Chamber has already bought $350,000 in the airtime to support Joyce in the race, and according to the Cleveland Plain Dealer will officially endorse him on Tuesday.

The Chamber has been getting increasingly involved in GOP primaries in recent weeks, stepping forward to back business Republicans over hard-line conservatives. The group endorsed Rep. Jack Kingston (R-Ga.) in his crowded Senate primary last week.

Joyce represents a swing district, and is favored in both his primary and the general election.