North Carolina state House Speaker Thom Tillis (R) narrowly defeated Sen. Kay Hagan (D-N.C.) on Tuesday in one of the nation's highest-profile Senate races.

The Associated Press called the race for Tillis after the polls closed, with the Republican leading Hagan by 2 percentage points. Libertarian pizza deliveryman Sean Haugh trailed far behind.

Hagan, who was first elected to the Senate in 2008, was considered one of this electoral cycle's most vulnerable Democratic incumbents. The Tar Heel State race was closely scrutinized as one that might contribute to a new GOP majority in the Senate. Republicans went into Tuesday's election needing to pick up six seats to gain control of Congress' upper chamber.

North Carolina's expensive television topography, with multiple key media markets, also helped drive spending in the contest to $111 million, making it the first general election Senate race to pass the $100 million mark.

The campaigns and their affiliated outside groups spent heavily on turnout efforts in a state that President Barack Obama won by just 11,000 votes in 2008 and lost by nearly 100,000 votes in 2012. While Tillis' campaign worked to tie Hagan to Obama, frequently repeating the claim that she had voted with the president "96 percent of the time," the senator's campaign did the opposite by trying to de-nationalize the race. In debates and on the airwaves, Hagan and her surrogates reminded voters of Tillis' leadership in the North Carolina legislature, which turned sharply to the right after Republicans gained control in 2010.

Tillis, in turn, worked to distance himself from his record as speaker and to moderate some of his policy stances in order to neutralize Hagan's attacks. He announced new support for making birth control available over the counter. And after he had campaigned in the GOP primary on his opposition to expanding Medicaid coverage to some 500,000 North Carolinians under the Affordable Care Act, he said during the general election that he would "encourage" North Carolina Gov. Pat McCrory (R) and the state legislature to consider a Medicaid expansion.

National Republicans harbored concerns that Tillis should have resigned his state House leadership role in order to campaign full-time. He was busy presiding over the North Carolina House through July. But Tillis caught up as autumn progressed. He seized on Hagan's admission that she had missed a Senate Armed Services Committee hearing on the Islamic State to raise money in New York City. Hagan's campaign countered by pointing out that Tillis had missed legislative sessions himself to engage in fundraising.

Still, the senator appeared to feel the need to counter Tillis' foreign policy attacks. In October, she became one of the first Democrats facing a close re-election contest to call for a temporary travel ban on non-U.S. citizens from countries in West Africa affected by the Ebola virus.