Democratic U.S. Senate candidate Cal Cunningham speaks to supporters in March. North Carolina is among the most competitive Senate races in the country this fall as Cunningham challenges incumbent Thom Tillis.

FILE – In this March 3, 2020 file photo, Democratic U.S. Senate candidate Cal Cunningham speaks to supporters during a primary election night party in Raleigh, N.C. North Carolina Sen. Thom Tillis was outraised nearly 3-to-1 by his Democratic challenger in the last quarter, according to campaign reports that signal a more precarious reelection bid for the Republican in the presidential battleground state. (AP Photo/Gerry Broome, File)