Republican Jeff Flake is Arizona's new U.S. senator after comfortably defeating Democrat Richard Carmona in a high-stakes, big-money race for a rare open Senate seat.

Flake won the statewide election by 51-46 percent, unofficial results show. Libertarian Marc Victor received 4 percent of the vote.

Flake came out on top in 11 of the state's 15 counties to inherit the seat of retiring Republican U.S. Sen. Jon Kyl. Flake, a six-term congressman, won by a wide margin in Maricopa County, the state's most-populous county.

Carmona, a former U.S. surgeon general, won his home county of Pima County and Santa Cruz, Coconino and Apache counties.

Flake, 49, becomes the 11th senator in Arizona's 100-year history and the sixth Republican senator, breaking a 5-5 tie between the two parties.

Like Sens. Kyl and John McCain before him, Flake makes the jump from the U.S. House, where he served six terms from a Central Arizona district.

In his victory speech, Flake emphasized that the country will have to reduce its debt.

"Not every vote I cast will be popular," he told supporters. "But I can guarantee you that every vote I cast, every decision I make, will be made knowing what's at stake and knowing that this state has to have a brighter future."

It was the first time that Arizona has chosen a new senator since 1994, when Kyl was first elected. The subsequent elections featured incumbents seeking re-election.

Over the past two months, Flake and Carmona engaged in an intense battle featuring dueling attack ads on TV and sharp jabs in showdown debates. Nearly $30 million combined was spent by the two sides - with Flake supporters outspending Carmona backers by nearly $3 million.

Carmona and Democrats tried to paint Flake as a career politician and Washington insider who has said "no" to everything in his 12 years in the U.S. House and done little to improve Arizona.

Flake and the Republicans attempted to brand Carmona as President Obama's "handpicked" candidate who would fall in line with the Democratic leadership. The GOP also hammered Carmona for past run-ins with colleagues and superiors, saying he didn't have the right temperament for the Senate.

In the end, Arizona voters chose Flake and his pledge to rein in government spending and regulations and to repeal "Obamacare" over Carmona's promise to take his independent spirit to Washington, D.C., to break up a gridlocked Congress.

With six-year terms and a history of U.S. senators from Arizona serving for decades, Flake could be in office for years to come. Flake said Arizonans can count on him working across the aisle to address the country's challenges.

"That's been my hallmark in the House," he said. "And I plan to do the same in the Senate."

Flake said he was relieved to be done with the grueling campaign.

"It will be nice to turn on the television and not see my ugly face," he said, laughing.

Carmona, 62, was considered the best Democratic U.S. Senate candidate in Arizona in decades. He made it a race but couldn't overcome the Republicans' 6-percentage-point advantage among the state's 3.1 million voters.

The loss extends two Democratic droughts that started when Dennis DeConcini of Tucson left the Senate in 1995. Since then, no Democrat or candidate from Tucson has won a U.S. Senate election in Arizona.

In an emotional concession speech, Carmona thanked his family, campaign staff and supporters and said the margin gives hope for Arizona.

"We didn't win tonight, but when you look at the results it's clear that Arizona is moving toward moderation," Carmona said.

The man whose résumé includes combat veteran, trauma surgeon, deputy and hospital director said Arizona is headed back to a time when leaders from both parties can work together.

Carmona said his campaign was driven by people who wanted to see Arizona take a more moderate, sensible direction.

"You did it because you were tired of seeing Arizona focus on birther bills instead of education," he said to loud applause.

Preliminary results of an exit poll conducted for The Associated Press and television networks showed that Flake drew support from white voters, while Carmona won high marks among Hispanics.

Votes among independents were nearly evenly split among the candidates, the exit poll showed.

Voters who named the economy as the top issue facing the country didn't necessarily prefer one candidate over the other, but those who said health care weighs most heavily on their minds favored Carmona, exit polls showed.

Liberals and moderates sided with Carmona, while Flake scored well among conservatives.

The Associated Press contributed to this story. Contact reporter Brady McCombs at 573-4213 or On Twitter @BradyMcCombs.