PHOENIX (AP) — More than 300 people who say their livelihoods depend on a coal-fired plant on a sprawling Native American reservation rallied in Phoenix Wednesday to request a 90-day delay in steps being taken to shutter it by 2019.

Demonstrators — including miners who extract the coal that fires the plant, plant employees, their relatives and tribal and union leaders — asked for more time to allow a potential buyer of the Navajo Generating Station in northern Arizona to work out the details of a purchase they said would save jobs and a major source of funding for the Navajo Nation and Hopi Tr...