The Republican Party of the Northern Mariana Islands will have to elect a new chairman and president after the former governor Benigno Fitial resigned.
The party's first vice-president, Rita Chong-Dela Cruz, says she has received Mr Fitial's resignation letter.
Mr Fitial resigned as governor in February, just days before the start of his impeachment trial in the Senate.
The Republican Party has not held a meeting since then, and Mr Fitial has not returned to the CNMI.
He is said to be recuperating from gallbladder surgery in the Philippines.
