For the second time in two weeks, super PACs will play a major role in determining the outcome of a U.S. Senate primary contest.
Republican Jon Bruning, Nebraska's attorney general, was expected to win in a cakewalk for the seat, soon to be vacated by retiring Sen. Ben Nelson, a Democrat. Instead, two underfunded insurgent candidates -- Don Stenberg and Deb Fischer -- are giving him a run for his money, thanks in large part to a handful of outside groups.
Bruning has the fundraising advantage, having raised more than $3.6 million for his campaign. Stenberg has raised about $750,000, while Fischer has raised less than $440,000 for the race, including $35,000 of her own money.
But heading into today's primary, conservative outside groups have spent more than $2 million on advertising, according to Federal Election Commission records, with nearly $1 million going toward ads attacking Bruning. The ads appear to have been effective -- Bruning's numbers have slipped, according to recent polls.
"This is an unusual amount of spending for a Nebraska primary," said Michael Wagner, an assistant professor of political science at the University of Nebraska-Lincoln. "I don't think the Bruning campaign foresaw this."
Last week, outside groups led by the conservative Club for Growth spent millions in the GOP U.S. Senate primary election in Indiana, where six-term incumbent Sen. Richard Lugar lost to Richard Mourdock, a tea party favorite.
The Club is again flexing its muscles in Nebraska, where it supports Stenberg. So far, its super PAC, called Club for Growth Action, has reported spending more than $714,000 opposing Bruning, mostly on radio and TV ads.
Only Sen. Jim DeMint's leadership PAC, known as the Senate Conservatives Fund, has spent more on independent expenditures. DeMint's group has invested more than $947,000 on messages touting Stenberg.
But while polls show that Bruning's standing has fallen, Stenberg hasn't experienced a boon. Instead, Fischer, who was endorsed by former Alaska Gov. Sarah Palin last week, has seen a last-minute surge.