(CNN) - The stage is set in one of the most important Senate races this year's midterm elections, a contest that could decide whether the Democrats or Republicans control the chamber next year.
Former Alaska Attorney General Dan Sullivan held off two other major candidates to win Tuesday's Republican Senate primary, and will now face off in the general election against first term Democratic Sen. Mark Begich. If the GOP can flip the seat in Alaska, and five others without losing any ground, they will win control of the Senate.
Sullivan topped 2010 GOP Senate nominee Joe Miller, with Lt. Gov. Mead Treadwell coming in third place. Miller, who was backed by former Alaska Gov. Sarah Palin, surged in recent weeks, but wasn't able to close the gap with Sullivan, who enjoyed a fundraising advantage over his opponents, and who had the support of many mainstream pro-Republican organizations.
Groups such as American Crossroads and the U.S. Chamber of Commerce, which tend to back establishment GOP candidates, supported Sullivan, as they saw him as the strongest Republican candidate to take on Begich. Sullivan also had the backing of the Club for Growth, which often endorses more conservative Republican candidates.
Sullivan, who was also the state's director of natural resources, came under attack for his ties to Alaska, and for his record in state government. Sullivan's originally from Ohio and didn't live in Alaska for a chunk of time last decade when he worked in the George W. Bush administration and in the military.
The attacks came not only from Sullivan's Republican primary opponents, but also from pro-Democratic groups that are backing Begich. Some of those groups spent big bucks to go up with ads critical of Sullivan.
In a victory statement, Sullivan tied Begich to Senate Majority Leader Harry Reid.
"Harry Reid tried to stop us, but his millions of dollars of attack ads didn't work. Mark Begich, his loyal lieutenant, has spent the last ten months trying to avoid talking about his failed record. Now is the time to focus on the real issues that matter the most to Alaskans. I look forward to painting a clear contrast between Mark Begich’s inability to move our state forward and my vision for a brighter and better Alaska," wrote Sullivan.
The Democratic Senatorial Campaign Committee quickly fired off a statement, saying "Sullivan is wrong for Alaska women, seniors, and middle class families."
"Sullivan is an Outsider and his campaign is bankrolled by Outside special interests that want to privatize Medicare and Social Security, eliminate a federal minimum wage, and protect tax breaks for companies that ship jobs overseas," added DSCC Deputy Executive Director Matt Canter, in a statement.
With the primary over, the amount of attention and outside money flowing into the Alaska showdown will only intensify.
Democrats have a 55-45 majority in the Senate (53 Democrats and two independents who caucus with the party). But in the midterms, the party is defending 21 of the 36 seats up for grabs, with half of those Democratic-held seats in red or purple states like Alaska.
CNN Political Editor Paul Steinhauser and CNN's Ashley Killough contributed to this story