Easley is a Democratic superdelegate who has served as the state's governor for two terms. His decision comes despite several recent polls showing Clinton trailing rival Barack Obama ahead of the state's May 6 primary.
Easley would be just the second superdelegate from North Carolina to endorse Clinton. Six of the state's 17 superdelegates have endorsed Obama.
A former state attorney general, Easley has focused largely on education programs during his eight-year tenure. He's called on both of the presidential candidates to take more about he issue.
The person spoke to the AP on a condition of anonymity because a formal announcement had not yet been made.