Mike Lee is the overwhelming favorite to win in November and replace Sen. Bob Bennett, who was ousted at the Republican convention in May amid a wave of anti-incumbent rage around the country.
Lee and businessman Tim Bridgewater beat out Bennett at the convention to advance to Tuesday's primary, which Lee narrowly won. He earned a nearly 4,000-vote lead with 99 percent of precincts reporting for about 51 percent of the vote to Bridgewater's nearly 49 percent.
"That is awesome," Lee told The Associated Press after the race was called.
"We had an army of really hard-fighting, hard-campaigning volunteers and they just refused to quit because they believed in a message and a 223-year-old document."
Bridgewater conceded Lee's victory and said he would support him in the general election.
"I think the problems this nation faces right now are out-of-control spending and defending the Constitution and I think Mike will work hard to defend those principles," he said.
Lee's mission is simple should he get elected: limit the role of government to what the founding fathers intended it to be. He wants to cut federal spending, repeal the new federal health care reform law, suspend congressional earmarks and mandate term limits.
Lee, 38, is a former clerk to Supreme Court Justice Samuel Alito and briefly served as former Gov. Jon Huntsman's general counsel. His father, Rex Lee, was a Brigham Young University law school dean and solicitor general under President Ronald Reagan, and his brother Tom Lee has been nominated to the Utah Supreme Court.
Lee readily acknowledges his childhood was different from most. He frequently tells tales of attending Supreme Court hearings with his father when he was 10 years old.
"It helped me develop an understanding of how the operations of government really do end up having an impact on people's lives. My dad was really good at explaining to us in very practical terms what his cases were about, why they were important, and being there and seeing him in action sort of helped me understand that," Lee said.
Lee and Bridgewater rose to prominence by promising to be more conservative than Bennett while reining in federal spending. Lee frequently dazzled GOP convention delegates by citing from memory articles and clauses in the Constitution.
"This is an amazing country and we've got some challenges we face in the country right now, but they're challenges we can overcome. We'll return to the principles that motivated the American Revolution," he said following his victory.
With Bennett out of the race, it was difficult to distinguish the two Republican candidates.
Both said they wanted to overhaul the process of awarding home-district pet projects while drastically cutting federal spending.
The two turned to criticizing each other's professional career choices. Lee attacked Bridgewater for working with a company that accepted federal stimulus money. Bridgewater said there were too many lawyers in Washington already.
Some voters said it was difficult choosing between them.
"Can I have half of one and half of the other? Seriously. I wish I could. I like Mike Lee's enthusiasm and go get 'em. I like Tim Bridgewater's business experience," said Alicia Jemmatt, a Salt Lake City voter, who ultimately chose Bridgewater.
Lee won by performing better in Utah and Washington counties, two of the most conservative areas of the state.
Utah's six-term senator, Sen. Orrin Hatch, did not endorse a candidate in the primary. Bennett endorsed Bridgewater.
Lee said he would have welcomed Bennett's backing, but he had plenty of endorsements of his own. They included the support of Attorney General Mark Shurtleff and Sen. Jim DeMint, R-S.C.
One of the founders of Utah's tea party movement, David Kirkham, endorsed Bridgewater. The California-based Tea Party Express spent $30,000 supporting Lee in the campaign's closing days, mostly on radio advertisements.
Lee advances to face Democratic nominee Sam Granato, a political newcomer who is a restaurateur and chairman of the Department of Alcoholic Beverage Control.
Granato immediately began courting Bridgewater's supporters.
"We are all Utahns and, in the end, I believe our many shared values far outweigh our few differences," Granato said in a statement.
"The answers to our nation's toughest problems are not held exclusively by Democrats or Republicans. If we put partisanship aside, I believe we can develop common sense solutions to the important issues, including a return to fiscal responsibility, sustainable economic growth and long-term job creation."