WASHINGTON (AP) - The Bush administration on Tuesday threatened to veto Senate legislation designed to improve health care on American Indian reservations, objecting to expanded labor provisions in the bill.

The legislation would boost screening and mental health programs at the Indian Health Service, increase tribal access to Medicare and Medicaid and prompt new construction and modernization of health clinics on reservations. The Senate began consideration of the legislation Tuesday.

The bill would also expand the Davis Bacon Act, which requires contractors and subcontractors to pay workers locally prevailing wages and fringe benefits, to apply to some of the new American Indian projects. The Bush administration said in a statement that the labor provision would violate long-standing administration policy.

Senate Indian Affairs Committee Chairman Byron Dorgan, D-N.D., said the bill is a first step in addressing the "crisis" in American Indian health care. The system is underfunded and inefficient, he said.

Rates of most leading causes of death for American Indians are much higher than the rates for the rest of the country. Rates of alcoholism, diabetes, cardiovascular disease and suicide are especially high.

"Today it is likely somewhere on an Indian reservation someone is dying who shouldn't have to die," Dorgan said on the Senate floor.