FLAGSTAFF, Ariz. — Tribes across the United States are wrestling with competing needs, restrictive laws and inadequate staffing as they try to meet a tight federal deadline on spending billions of dollars in virus relief funds.

Congress set aside $8 billion for tribes that must be spent by the end of the year and meet strict federal guidelines. Otherwise, the tribes risk having to send it back.

Officials on the vast Navajo Nation have received $714 million in aid but approved just $60 million for health care, protective equipment and front-line workers against the virus.

Rifts between the tribal government’s legislative and executive branches have delayed putting more of the money to use.

Under the Treasury Department guidelines, the money can’t be spent on items already budgeted, back-filling lost revenue or per-capita payments. Tribes nationwide are lobbying their congressional delegation to extend the spending deadline and allow for more flexibility.