Heagarty, one of six candidates for the seat, was chosen unanimously by a group of 30 Democratic Party officials in the 41st House District.
Nichols says the race in 2010 will likely be one of the most contested seats in the 2010 election in North Carolina, as the Republican party lost the seat to Harrell, and they want it back.
The other five candidates have said they will not run for the seat in 2010, leaving Heagarty no Democratic challengers to the seat.
Governor Bev Perdue will appoint Heagarty next month, after she returns from China.
Harrell resigned his seat in September after an investigation was launched over some of his campaign spending.