This year's North Carolina Senate race has been extremely close, with Kay Hagan and Thom Tillis trading leads over the summer.

According an average of polls by Real Clear Politics, Hagan, a Democrat, and Tillis, a Republican, have been fighting for the lead from May to August. Hagan had a 0.8 point lead in early May, but Tillis pulled ahead from late May to late June. Hagan again took a slight lead from July to early August, but Tillis has pulled ahead in recent weeks. However, not all polls have Tillis in the lead at this stage. Real Clear Politics explained that this is characteristic of the the North Carolina U.S. Senate race in particular.

“The North Carolina Senate race is one of the most dynamic, active races we’re seeing in this part of the year,” the polling aggregator said in a statement to The Chronicle. “We’ve been following it very closely and even we cannot say for sure who has the decisive lead.”

Several factors may be keeping this race tight, most notably the close party ties of the candidates, said Mac McCorkle, professor of public policy at the Sanford School of Public Policy.

“The race so far has been essentially a referendum of Hagan and the Obama administration versus Tillis and the Republicans of Raleigh,” he said. “Both of the incumbents are very tied to their parties, more so than any race in the past.”

Both candidates have been closely aligned with their respective parties for many years prior to their candidacy. In addition to being Speaker of the N.C. House, Tillis served as a Republican member of the N.C. House of Representatives for seven years. Hagan, as an incumbent candidate, has held North Carolina's Senate seat as a Democrat since 2009.

McCorkle also said that education is a hot-button issue in these elections, especially as the race nears its end—and this can spell bad news for the Republicans.

"The race is more and more depending on the issue of public school education,” McCorkle explained. “Because the previous Republicans have been so closely tied to many of the issues faced in North Carolina education, this can cause people to perceive Tillis in a negative light.”

Durham Public Schools in particular have had problems in the past year, including the resignation of the former superintendent, who was accused of making fraudulent credit card charges to the districts’ account. Many other education issues have been in the news, especially the development of early childhood education in Durham schools.

McCorkle said that looking forward, both candidates may be impacted by the third party candidate in the race, Sean Haugh.

“This race is particularly unique because of the strength of Sean Haugh and his backing as a member of the libertarian party,” McCorkle said. “He has had considerable support as the third-party candidate, and I feel that this is something that both parties have to watch out for, in terms of Haugh’s power to draw votes away from them.”

Robert Lopez—a representative of USA Today polls—said that there’s no way to predict the overall outcome.

“I wish I could comment more succinctly, but honestly, there’s no telling at this point,” Lopez said. “We can predict the issues and the chances, but that’s all we can do—predict.”