Democratic U.S. Senate candidate Jason Kander conceded early Wednesday, ending his spirited bid to unseat incumbent Republican Roy Blunt in a race both parties had eyed as potentially pivotal in the battle over control of the chamber.

Blunt, 66, served seven terms in the House before winning election to the Senate in 2010. He'd never faced a close race before, but polls showed this election was tight from the outset as Kander, Missouri's 35-year-old secretary of state and a former Army intelligence officer who served in Afghanistan, emerged as one of the surprise candidates in any Senate race.

In a short concession speech, Kander urged people of his generation to stick with politics despite the somber election results.

"They need to know that I'm not OK with them stepping away, that this country is a place you've got to stay invested in," Kander told supporters in Kansas City. "This generation is not going anywhere."

Blunt relished a hard-fought victory.

"What a great moment for our state," he told supporters in Springfield, soon after receiving a concession call from Kander.

Blunt dominated the rural areas of the state, offsetting Kander's advantage in the St. Louis and Kansas City areas. His win was part of a GOP sweep in Missouri in statewide offices mostly dominated previously by Democrats. Republicans also won races for governor, lieutenant governor, attorney general, secretary of state and treasurer.

National senatorial committees for both parties and a wide array of political action committees and other groups combined to spend millions of dollars on the Missouri race, which some thought might decide control of the Senate.

Kander ran on the need for a new generation of leadership, often seeking to portray Blunt as a Washington insider with a wife and three children who are lobbyists. The message resonated with many voters, including Jim Moore, 75, a retired management consultant from Chesterfield who said he voted for Kander because "we need to have a new voice in Washington representing Missouri."

But Mary Beck, a 61-year-old assistant nursing professor from Columbia, said she voted for Blunt because of his experience. She said it takes time to "have influence and to understand how to work with the other players at the U.S. Capitol."

Kander spent the campaign playing up his military experience, most notably with a TV ad showing him putting together an assault rifle while blindfolded and daring Blunt to do the same.

Blunt campaigned on such core believes as a need for more and better jobs and the elimination of unnecessary regulations and the Affordable Care Act. He also criticized Kander's handling of election problems as secretary of state, including a ballot shortage at some St. Louis County precincts in the April election and a state legislative primary in St. Louis city in August that had to be redone because of absentee ballot concerns.

Blunt was elected Missouri secretary of state in 1984 and re-elected four years later. After a failed gubernatorial bid in 1992, he was elected to the House in 1996 and re-elected six times, winning by wide majorities each time. He was House Majority Whip from 2003 to 2007. He defeated Democrat Robin Carnahan by a 54 percent to 41 percent vote in 2010 to win a seat in the Senate.

Kander served two terms in the Missouri House before winning election as secretary of state in 2012. What happens next for him isn't clear: The next senatorial election in Missouri is in 2018, but the incumbent is a fellow Democrat, Claire McCaskill.