State Sen. Deb Fischer has won the Nebraska Republican Senate primary, setting up a matchup with former senator Bob Kerrey (D) for the seat being vacated by retiring Sen. Ben Nelson (D).

The result is a major upset; until last week, state Attorney General Jon Bruning was the overwhelming favorite in this primary. Throughout the race, he had the most money and establishment support.

Many will argue that Fischer’s victory is the latest in a line of tea party upsets. But it was state Treasurer Don Stenberg who attracted support from conservatives put off by Bruning’s college liberalism, rather than Fischer. It was only in the past week that Fischer won the support of former Alaska governor Sarah Palin and former Godfather’s Pizza CEO Herman Cain.

The Club for Growth and the Senate Conservatives Fund (backed by South Carolina Sen. Jim DeMint) combined to spend more than $2 million on the race against Bruning and in support of Stenberg.

While Stenberg never took off, that money may have weakened Bruning, giving the under-funded Fischer an opening. Bruning also suffered from a series of tough headlines in the local media — coverage that undoubtedly would have been at issue in the general election.

Fischer’s campaign released a poll this week showing her in striking distance of Bruning, and he started attacking her in ads for the first time.

Because of that late surge, Bruning’s campaign hoped that it’s large advantage in absentee voting would pay dividends on primary day, but Fischer won overwhelmingly on ballots cast Tuesday.