The Trump administration's $1 billion budget request for the Bureau of Land Management (BLM) seeks $66.7 million for the Wild Horse and Burro Management program and a continued push to eliminate annual appropriations bill riders that prohibit the sale or killing of the federally protected animals.

Congress has yet to act on the administration's 2018 budget request, which also requested lifting the appropriations riders.

"The 2019 budget continues to propose the elimination of appropriations language restricting BLM's use of all of the management options authorized in the Wild Free-Roaming Horse and Burro Act," the Interior Department's plan states, in reference to the 1971 law that calls for the "protection, management and control" of the animals on public land.

"This change will provide BLM with the full suite of tools to manage the unsustainable growth of wild horse and burro herds."

For more than a decade, Congress has used appropriations bill riders to prohibit the BLM from spending taxpayer money on "the destruction of healthy, unadopted, wild horses and burros in the care of [BLM] or its contractors or for the sale of wild horses and burros that results in their destruction for processing into commercial products."

The BLM uses helicopters to round up thousands of wild horses and burros from public lands each year. About 45,000 captured animals are held in government corrals and pastures, costing taxpayers $50 million annually. Another 67,000 wild horses and burros roam around on federal land.

The bureau asserted last year that a high number of "excess wild horses and burros causes habitat damage that forces animals to leave public lands and travel onto private property or even highways in search of food and water" and requested that Congress remove some restrictions on the sale and disposition of "excess" animals.

The American Wild Horse Campaign (AWHC) condemned the president's latest budget proposal. The horse advocacy group worries that the animals in holding and those considered "excess" on the range would be killed en masse if Congress were to grant the BLM's budget request.

"The Trump administration continues to defy the will of the American people by proposing the slaughter of America's iconic wild horses and burros," said Suzanne Roy, executive director of the American Wild Horse Campaign.

A poll cited by the AWHC showed that 80 percent of Americans—including 86 percent of Trump voters and 77 percent of Clinton voters—oppose the slaughter and mass killing of wild horses and burros.

"The administration's decision to prioritize slaughter over humane management alternatives recommended by the National Academy of Sciences is irresponsible, reckless and politically unacceptable," Roy said.

A 2013 National Academy of Sciences review of the BLM's Wild Horse and Burro Management program found that a birth control vaccine was among the most safe, effective and economical ways to humanely reduce horse reproductive rates on the range.

But according to the AWHC, the BLM "has refused to use this method in more than a token manner, opting instead for costly and cruel helicopter roundups."