WASHINGTON (AP) - The Supreme Court won't hear a Republican-backed challenge of federal campaign finance restrictions.

The court on Monday refused to hear an appeal by former Louisiana Rep. Anh "Joseph" Cao and the Republican National Committee.

Cao wanted the Supreme Court to declare unconstitutional the $42,000 federal limit on what state and national parties could spend in 2010 in coordinated efforts on behalf of a candidate in his race. Currently, the state and national parties cannot consult with each other on money spent beyond that limit.

State party leaders have said that can lead to duplicative or contradictory messages.

The 5th U.S. Circuit Court of Appeals said the campaign finance limit was constitutional.

Cao lost his seat last year to Democrat Cedric Richmond.

The case is Cao v. Federal Election Commission, 10-776.