(CNN) -- Nebraska state Sen. Deb Fischer won the Republican nomination for an open U.S. Senate seat on Tuesday, official results showed, beating two better-funded candidacies for the opportunity to face off against a former U.S. Senator for the open seat in November.
Fischer's upset toppled state Attorney General John Bruning, seen as the establishment candidate, and state Treasurer Don Stenberg, seen as the tea party favorite.
The senate race in Nebraska was the most closely watched contest on Tuesday, when GOP voters there and in Oregon cast ballots in the presidential race.
Presumptive Republican nominee Mitt Romney was projected to win the presidential tally in Nebraska, standing at 71% with all precincts reporting, according to the Secretary of State website. In Oregon, he was ahead with 72% of the vote out of 100% of precincts tallied.
Former Sen. Rick Santorum of Pennsylvania had approximately 14% of the Nebraska vote, several weeks after he suspended his White House bid. Texas Rep. Ron Paul had approximately 12% in the Oregon contest, held days after he announced that he would no longer actively campaign for the GOP nod.
In the Nebraska senate race, Brunning and Stenberg, along with their allies, spent millions against each other, while Fischer picked up late endorsements from former Alaska Gov. Sarah Palin and one-time GOP presidential hopeful Herman Cain.
She now goes head-to-head against former U.S. Sen. Bob Kerrey, who represented the state from 1988-2000, then chose not to seek reelection.
The retirement of Sen. Ben Nelson, a Democrat, left an open seat and political trends there have led to independent handicappers favoring a Republican win come November.
Fischer sailed relatively under the radar as Bruning and Stenberg waged war against each other and Kerrey, who was presumed as the Democratic nominee, faced Republican challenges to his residency in Nebraska. After stepping down from the Senate in 2001, Kerrey lived and worked in New York.
The majority of tea party-aligned individuals and groups split between Fischer's two rivals.
Bruning received the support of Arkansas Gov. Mike Huckabee, former Sen. Rick Santorum of Pennsylvania, the U.S. Chamber of Commerce, and the Tea Party Express. "The federal government spends too much, taxes too much, regulates too much, and listens too little," he posted on his website.
Stenberg -- hardly a political outsider -- was waging his fourth campaign for the U.S. Senate, and he won the party's nomination once. That was the year 2000, and he eventually lost the general election to Nelson. He was backed this cycle by the PAC behind the tea party, FreedomWorks, as well as Sen. Jim DeMint of South Carolina and the Club for Growth.
Long before GOP voters chose their nominee on Tuesday, two prominent and independent political handicappers rated the race as leaning towards the eventual Republican nominee.
Reliable polling in the state has been scarce, but watchers of the race perceived Fischer as closing a gap between her and Bruning in the final days.
The Cook Political Report lists the race as "likely" a Republican pickup -- which falls between "solid" and "lean" -- while the Rothenberg Political Report calls it "Republican favored," one step below a safe seat but three steps above a toss-up.
A win in Nebraska would help Republicans wrestle a simple majority in the U.S. Senate from Democrats, a feat the GOP is four seats away from achieving.
Democrats, meanwhile, are defending or facing a retirement in 23 of the 33 Senate seats up for election this year. And of the 10 open seats, seven are held by Democrats and three by Republicans.
While the GOP candidates exchanged elbows through a series of television advertisements, they found time to beat up on Kerrey and were joined by national operations, such as the American Crossroads committee founded by Karl Rove.
Within days of Kerrey's decision to enter the race -- he initially said he would not run, then two weeks later, announced he would -- Bruning was on the air with an ad questioning the former senator's residency and the influence of the former Cornhusker senator's time in New York.
Kerrey is a "New York liberal," Bruning's ad went, while American Crossroads said, "A decade in Greenwich Village changed Bob Kerrey."
The group also seized on his reluctance to enter the race, claiming in a radio ad that Kerrey "cut his own secret deal with Democratic leaders in Washington, a deal so secret Kerrey won't talk about what promises were made."
The state Republican Party even filed an official challenge of his residency with the Secretary of State's office.
Kerrey's campaign manager, Paul Johnson, told CNN in March that the residency attacks were "insulting to Nebraskans" and that Bob is "a fiscal conservative" concerned with national debt and budget deficit.
Other attacks have sought to tie Kerrey to outgoing Nelson -- who provided the 60th vote for Democrats to pass the health care overhaul.
He agreed to support the bill after negotiating a compromise, which came to be known as the "Cornhusker Kickback." It would have modified federal abortion funding regulations and saved the state approximately $100 million on Medicare costs over a decade.
As Republicans at home and nationwide protested, he had the provision removed, and said he did not wish his state to have an advantage over other states.
Like others in the upper chamber who are retiring willingly or unwillingly this year, Nelson is known for casting votes with both sides of the aisle.
This open seat has taken a backseat in prominence to other states' races, such as last week's primary defeat of Republican incumbent Sen. Richard Lugar in Indiana.
But Nebraska has a front seat to an issue splitting the two parties this year.
The controversial Keystone XL oil pipeline, generally favored by Republicans and opposed by Democrats, was to stretch from Canadian oil sands to the Gulf Coast, bisecting Nebraska. But environmentalists worried about polluting the Ogallala Aquifer, which supplies most of the state with drinking water.
Nelson, the outgoing senator, easily won a second term in 2006, but as it became clear that Republicans considered his seat in play this cycle, Nelson made a December announcement that he would not seek a third term.
"Simply put: It is time to move on," Nelson said at the time.
Nebraska is expected to be anything but tranquil as the race between Fischer and Kerrey heats up this summer.
Don Walton, a political writer with the Lincoln Journal Star, had a simple warning in his pre-election Sunday column: "buckle up."