The complaint filed Tuesday with the Federal Elections Commission alleges that the Nebraska Democratic State Central Committee, using money provided by national Democratic campaign groups, spent hundreds of thousands of dollars more on television ads promoting Nelson than it is legally permitted to do. It also alleges that the disclaimers at the end of the ads were inconsistent and misleading in identifying who was paying to put Nelson on TV.

"Nebraskans deserve to know the exact amount of illegal spending that has occurred by the NDSCC  — and that Washington dollars paid for it — and why Ben Nelson is an active participant in this blatantly illegal act," said Mark Fahleson, who chairs the state GOP.


The case boils down to the nuances of whether spending by campaign committees is "coordinated" or "independent" of a candidate. Republicans argue that the ads were coordinated and thus put Democrats over the legal limit.

Democrats dismissed the allegations as a distraction, but didn't specifically address whether the spending violated FEC rules. They strove to change the conversation back to allegations that Bruning violated conflict of interest guidelines by investing in a vacation home with executives who had benefited from decisions he made as the state Attorney General.

"Instead of coming clean about his shady investments and allegations that he used his position as Attorney General to line his pockets, Bruning is trying to push his unethical investments under the rug," said Democratic Senatorial Campaign Committee spokesman Matt Canter.

The FEC complaint came at the same time as a new poll showing both Nelson's and Bruning's popularity slipping in Nebraska, but Nelson climbing in a matchup between the two.

The poll released Wednesday by Democratic firm Public Policy Polling showed that 36 percent Nebraska voters approve of Nelson and 55 percent disapprove, compared to January, when 39 percent approved and 50 percent disapproved.

Bruning's approval rating has dropped from 42 percent in January to 32 percent at the end of September. And while in a Bruning-Nelson matchup, Bruning led by 11 points at the start of the year, he now holds only a 4-point lead over Nelson.

Nelson, who served as Nebraska's governor for two terms, has not yet announced whether he will seek reelection to the Senate. Although he won in 2006 by almost 30 points over Republican Pete Rickets, his seat is one that Republicans are most optimistic about flipping in 2012.

Republicans have also raised the question of whether the heavy spending by national Democratic groups on Nelson this early in the season reflects concerns that Nelson will retire instead of seeking reelection unless Democrats spend big to shore up his prospects. They point to other Democratic senators who are also endangered but have not seen the level of national investment evident in Nebraska.