Tillis is a first term incumbent who won by less than two points in an historically Republican midterm cycle. Tillis won by a mere 1.7 points in 2014 — barely beating a Democratic incumbent in a year in which Republicans took the Senate. In 2020, he starts off with two major disadvantages: Democrats turn out in higher numbers in presidential cycles, and he’ll share the ballot with an historically unpopular president.
No single political party has dominated North Carolina in recent years. Tillis’s seat may have switched from Democrat to Republican in 2014, but the following cycle saw a Democratic governor win the state, even as Trump won the presidential contest. North Carolina is a perennial swing state, and is likely to receive intense, sustained national attention through the 2020 election — meaning more eyes will be on Tillis, more money will flow to his opponent, and more enthusiasm on the ground could boost Democrats.