TUBA CITY, Ariz. (AP) – The Navajo Nation Supreme Court has scheduled oral arguments in a case challenging a presidential candidate's ability to speak Navajo.

The candidates are required under tribal law to speak Navajo fluently and understand it.

Dale Tsosie contends that Chris Deschene lied about being fluent when he entered the race to preside over the country's largest American Indian reservation.

Deschene says fluency is a matter of opinion and that his language skills are progressing.

The tribe's Office of Hearings and Appeals dismissed Tsosie's grievance, saying it was untimely filed. Tsosie appealed to the high court.

Arguments are set for Sept. 26 in Tuba City.

Deschene and former Navajo President Joe Shirley Jr. are set to face off in the tribe's general election in November. Tsosie placed tenth in the primary.