Republicans filed a complaint with the Federal Election Commission this week against Sen. Ben Nelson (D) and the Nebraska Democratic Party.

Nebraska Republican Party Chairman Mark Fahleson accused Democrats of buying $458,600 worth of coordinated television advertisements on Nelson’s behalf, which he says is twice the legal limit.

Nelson is one of the most vulnerable Democrats up for re-election in 2012. Democrats have pounded the local airwaves with advertisements on his behalf to boost his bid.

Fahleson also charged the ads are not attributed properly to Democratic entities.

Nebraska Democratic Party spokesman Brandon Lorenz said the complaint is without merit.

Three Republicans are seeking their party’s nod to face Nelson: state Attorney General Jon Bruning, state Sen. Deb Fischer, and state Treasurer Don Stenberg.