The U.S. Chamber of Commerce endorsed Blue Dog Democrat Rep. Walt Minnick (Idaho) Tuesday.

Minnick voted against the Disclose Act last week, the Democrats' campaign finance legislation that was strongly opposed by the Chamber. The powerful business trade group scored the vote, which meant it factored lawmakers' vote into its endorsement decision.

Minnick is a top GOP target this cycle. Sen. John McCain (R-Ariz.) carried his district in the 2008 presidential election by 26 points.

But the first-term lawmaker has amassed a conservative voting record. He voted against the healthcare reform bill, the stimulus package and climate change bill.

He is the only Democrat to be endorsed by the national Tea Party. However, he will face Republican Raul Labrador in November. Labrador has local Tea Party backing.

The Chamber endorsed conservative Democratic Rep. Dan Boren (Okla.) before the House voted on the Disclose Act, in what some saw the move as a way of pressuring lawmakers who were undecided about the legislation.