According to the Asheboro Courier-Tribune, Crisco, 71, suffered a fall at his home in Asheboro and was dead when emergency services arrived.
Crisco and Aiken were both vying for the Democratic nomination for North Carolina's 2nd Congressional District. The primary results were considered too close to call, with Aiken ahead by only 369 votes.
The candidates were waiting for word from election officials on how to proceed. On Wednesday, Crisco said he wasn't ready to concede.
The Democratic nominee will run against incumbent Rep. Renee Ellmers (R-N.C.)