North Carolina Gov. Roy Cooper opted not to be a candidate in Vice President Kamala Harris' running mate search, two people familiar with the matter said Monday, in part because of concerns that his Republican lieutenant governor would assume control when he travels out of state if he were selected.

Cooper, 67, withdrew before Harris formally began soliciting vetting material from potential vice presidents, the people said. They spoke on the condition of anonymity to discuss the sensitive search process. Harris' search is ongoing and her teams of lawyers and political aides are still reviewing information on a narrowing list of potential candidates.

Cooper, the former chairman of the Democratic Governors Association, has been close to Harris since they were both state attorneys general. His potential selection was seen as a possible asset in shifting North Carolina — the Democrats' only significant opportunity to expand on their 2020 map — into Harris' hands.

Under the state constitution, North Carolina Lt. Gov. Mark Robinson, who is the GOP's nominee to replace the term-limited Cooper, becomes acting governor and can assume the Democrat's powers when he travels out of state.

Cooper, according to one of the people, has expressed concern about what Robinson might do if he were to leave the state extensively for campaign travel.

Robinson is an ardent social conservative, who once called abortion “child sacrifice.” In various church pulpits, Robinson has asserted men as the rightful leaders in church and society. He once mused that leaders of the original birth control movement in the U.S. were “witches, all of ’em.” He has discussed LGBTQ people with words like “filth” and “maggots."

The New York Times first reported that Cooper had withdrawn himself from the process, but did not detail the timing of his decision or his rationale. The Harris campaign declined to comment.

Spokespeople for Cooper didn’t immediately respond to emails and phone messages late Monday.