(CBS News) Nebraska state Senator Deb Fischer pulled off a surprise upset victory against Nebraska Attorney General Jon Bruning in the state's Republican Senate primary Tuesday, marking the second contest in two weeks in which an establishment favorite was upended by a dark horse candidate in a Senate primary.
Fischer, a rural rancher from the state's 43rd legislative district, eked out a 5-point victory over Bruning, winning 41 percent to the Attorney General's 36 percent with nearly all the votes counted. State Treasurer Don Stenberg earned 19 percent.
As of just a few weeks ago, Bruning was widely considered the favorite in the race, and was expected to handily defeat Fischer and Stenberg to face off against Democratic candidate Bob Kerrey in November.
In recent days, however, some signs suggested the. While Bruning was hit with a series of scathing attack ads -- a number of which were funded by outside groups supporting Stenberg -- some polls showed Fischer surging.
Fischer secured the endorsements of former Alaska governor Sarah Palin and former presidential candidate Herman Cain, and she also got a boost from Joe Ricketts, the owner of the Chicago Cubs and founder of TD Ameritrade, who over the weekend injected $200,000 into the race for advertisements blasting Bruning and touting Fischer, according to the Omaha World-Herald.
The state Senator was not the only candidate boasting high-profile endorsements, however: Bruning recently received the backing of former presidential candidates Rick Santorum and Mike Huckabee; meanwhile, two major conservative groups - the Club for Growth and South Carolina Sen. Jim DeMint's Senate Conservatives Fund - both backed Stenberg, as did DeMint himself.
Jennifer Duffy, who covers Senate and governor races for The Cook Political Report, argues that Fischer's victory was in part a product of the fact that she faced two fairly flawed competitors.
"Sometimes we get so wrapped up in this Tea Party/establishment/non-establishment stuff that we forget the basics," Duffy told Hotsheet following Fischer's victory Tuesday night. "I think that there were a lot of basics here."
Pointing to ethics charges leveled against Bruning and Stenberg's three previous failed Senate bids, Duffy argues that Fischer stood out as a reasonable alternative to two candidates with obvious flaws.
"She was a woman who ran a good campaign who had a good profile for this state. People relate to her," Duffy said. "So when voters went looking for an alternative, it's not hard to see how they were fine with voting for her."
Still, Fischer faced a significant fundraising disadvantage in the race.
According to the Center for Public Integrity, Bruning raised more than $3.6 million for his campaign, and Stenberg raised approximately $750,000. Fischer, on the other hand, reportedly raised less than $440,000 for the race, $35,000 of which was her own money.
Outside groups also contributed significantly, pouring more than $2 million into advertising. According to the Center for Public Integrity, nearly $1 million of that went toward attacking Bruning.
The Club for Growth -- which spent heavily in last week's Indiana primary, where longtime Republican Senator-- spent more than $700,000 on ads attacking Bruning, while DeMint's Senate Conservatives Fund put nearly $1 million into supporting Stenberg.
Fischer was "pretty much shut out of the fundraising" in the primary process, according to Duffy, in part because of her relatively late entrance into the race.
"She's got a lot of work to do," Duffy said. "She's got to raise money."
Still, Duffy says Fischer could pose more of a threat than either of her challengers might have to Kerrey -- a former Nebraska Senator and governor who serves as Democrats' best hope of eking out a victory in the solid red state.
"Now they face a nominee who doesn't have very obvious flaws," Duffy said. "Yes, she's undefined and they will try to define her quickly, but Democrats, despite what they don't say now, really, really wanted to run against Bruning. They just felt like there was such a case to be made."
"In a lot of ways, she is the tougher general election candidate," Duffy added.
In a statement released shortly after the race was called, the Democratic Senatorial Campaign Committee (DSCC) called the match-up "promising" for Democrats, and touted Kerrey's history as a "proven winner."
"These results set up a promising general election match-up between Bob Kerrey, a proven independent leader, and Deb Fischer, an untested hypocritical politician whose record and positions have never been scrutinized," said Matt Canter, spokesman for the DSCC. "Bob Kerrey is a proven winner with an honorable record of service to the country, working with both parties to solve problems, while Fischer is an untested Tea Party candidate who has profited off a federally subsidized sweetheart land deal and called for higher gas taxes on middle class families in Nebraska."
DeMint, meanwhile, quickly urged Republicans to rally around Fischer.
"Congratulations to @DebFischer2012 for winning a come-from-behind victory. Now it's time for all Republicans to unite behind her," he wrote in a Tweet.