Washington (CNN) -- First-term Democratic incumbent North Carolina Sen. Kay Hagan lost in a tight contest against GOP challenger Thom Tillis, according to a CNN projection. 

It was the most expensive Senate race this cycle: A great deal of the funding was provided by out-of-state organizations backing harsh television attack ads. 

The neck-and-neck race was key to Republicans' plans to win back the Senate from Democrats. With 99% of precincts reporting their vote totals, Tillis had 49 % to Hagan's 47%. 

Tillis is known for his conservative stances on issues like same-sex marriage and women's abortion rights. He worked to nationalize the race by tying Hagan to President Obama, who suffers from high disapproval ratings in the Tar Heel state even though he -- along with Hagan -- were victorious there in 2008. 

Tillis made national news in late October when he debated an empty chair on live television after his opponent refused to attend what was initially billed as a debate between the two candidates. 

Hagan launched aggressive attacks on Tillis' tenure in the state legislature, highlighting how his legislature cut unemployment benefits, slashed funding for education and prohibited the expansion of Medicaid under the Affordable Care Act. She also worked to bolster her own appeal with racial minorities by pointing out Tillis' enactment of a strict voter identification law. 

Neither candidate has enjoyed much popularity in the state according to an NBC News/Marist poll from last week showing Hagan's disapproval rating at 48 percent and Tillis' at 44 percent. 
Which party?
race was key to Republicans' plans