A leading Native American Chief has warned a looming US Government shutdown threatens "lifelines that maintain the health, culture, and safety of our people" should crucial funding deadlines go unmet.

US Government shutdowns occur when Congress fails to pass 'appropriation bills' - meaning funding legislation or budget, meaning federal agencies stop all non-essential operations.

At present, deadlines beginning on March 1 with others in the days following are approaching.

The March deadline was an extension made on avoiding a partial shutdown in January.

Cherokee Nation principal chief Chuck Hoskin Jr wrote to Speaker of the US House of Representatives last week, ahead of the National Congress of American Indians meeting, in the nation's capital to signal his warnings and a plea.

"As the Principal Chief of the Cherokee Nation – the largest tribal nation in the United States with citizens living in every state across the country, including Louisiana – I write to draw your attention to the devastating impact that a federal government shutdown will have not only on Cherokee Nation in particular, but also for Indian Country as a whole," he wrote.

"I hope you will take this danger into account.

"Essential services that our citizens rely on, such as health care provided through the Indian Health Service, critical education programs, and public safety provided by federal funding will be severely curtailed if Congress fails to keep the government open. These services are not luxuries but lifelines that maintain the health, culture, and safety of our people."

Chief Hoskin said a shutdown would mean over 140,000 Cherokee Nation citizens would go without groceries; over 12,000 could lose access to diabetes and cancer treatments; over 1,300 would lose out on workplace training "they are pursuing to find good-paying, full-time jobs"; and "Detention agreements will have to be canceled, which could release 85,000 criminals before their sentences are served".

He said an environment of uncertainty around tribal economic development has built, with abilities to exercise sovereignty and self-determination also threatened by a potential shutdown.

Chief Hoskin said "repercussions will be magnified" across Indian Country where "many tribal nations rely on federal support for basic services to meet the needs of millions of Native Americans".

"I implore you, as Speaker of the House, to consider the broader implications of a government shutdown on Indian Country. It is critical that the United States honor its commitments and responsibilities by finding a resolution that averts this crisis. Thank you for your attention to this critical matter," he wrote.