In a move by the International Olympic Committee that apparently could block Sebastian Coe as an expected presidential candidate, the Olympic governing body has clarified its new and complex election rules before a deadline on Sunday to enter the race.

A letter was sent by the IOC’s ethics commission to the 111 members, including Coe and several more likely candidates in the contest to succeed Thomas Bach next year.

Details in the letter dated Monday specified why Coe, the 67-year-old president of World Athletics, would seem ineligible to complete a full first IOC mandate of eight years without at least getting special exemptions to remain a member of the Olympic body.

The winning candidate must be a member of the IOC on election day, scheduled for March in Greece, “and during the entire duration of their term as IOC President,” the letter stated.

Coe’s IOC membership is conditional on being president of World Athletics, a role he must leave in 2027 on completing the maximum 12 years in office.

Another candidate, IOC vice president Juan Antonio Samaranch Jr., who turns 65 in November, could have legal issues with the standard age limit of 70.