RENO, Nev. >> Congress is closer to approving a contentious wild horse initiative backed by national animal welfare groups and the livestock industry but condemned by leaders of the largest and oldest coalition of mustang advocates in the West.

The Senate Appropriations Committee approved $35 million last week for the program supported by an unprecedented alliance including the Humane Society of the United States, American Society for the Prevention of Cruelty to Animals, National Cattlemen’s Beef Association and American Farm Bureau Federation.

They say it would eliminate the threat of slaughter for thousands of free-roaming horses and shrink the size of herds primarily through expanded fertility controls on the range.

Critics say it drops long-held opposition to the capture of mustangs across 10 western states and could allow for sterilization of mares — a hot-button issue with horse protection advocates historically.

“It’s a sweeping betrayal of America’s wild herds by the nation’s largest animal welfare groups,” Suzanne Roy, executive director of the American Wild Horse Campaign, said following Thursday’s vote.

The Senate committee included a $35 million increase for the U.S. Bureau of Land Management’s wild horse and burro program as part of the $35.8 billion Interior Department appropriation bill it approved on Thursday. It’s not clear when the full Senate will consider the measure.

Then-Acting BLM Director Casey Hammond said in Idaho in July the Trump administration won’t pursue lethal measures such as euthanasia or selling horses for slaughter.

Backers of the bill approved by the Senate panel said it provides added assurances the horses will be treated humanely. They had sought a $50 million increase in the BLM’s $80 million annual horse budget, arguing any boost in spending on contraception and other population controls ultimately will save money as herds shrink.

“This is a historic moment for our herds, containing the strongest language protecting wild horses and burros we have ever seen in an annual appropriations bill,” Matt Bershadker, president and CEO of the ASPCA, said in a statement emailed to The Associated Press on Friday. He said it increases “commitments to protect these animals from killing or sale to slaughter.”

The new alliance unveiled in April was immediately attacked by the American Wild Horse Campaign, Friends of Animals and others who have fought legal battles for more than a decade to block mustang roundups.

If implemented, “we’ll see massive round-ups, swelling captive wild horse population and jubilation from cattlemen’s associations that secured political cover from the Humane Society … for their long-time aspiration to secure a government-funded wild horse depopulation program,” Marty Irby, executive director of Animal Wellness Action, said after the vote.

BLM estimated 88,000 wild horses and burros are roaming public rangelands, more than three times what the agency says the land can support. Another 50,000 that have been removed from the range in recent years were in holding facilities at an annual cost of about $50 million.

Horse advocates have argued the animals must be permitted to roam the range in federally protected management areas established under the Free-Roaming Horse and Burro Act of 1971. They say BLM’s population quotas are often outdated and lack scientific data to support roundups to cull herd sizes.

Ginger Kathrens, director of The Cloud Foundation based in Colorado, said the new initiative dubbed the “Path Forward” should be called the “path to extinction.” She said it sets population targets to less than 27,000 — the total when federal protections first were enacted nearly a half-century ago.

“The extinction-level number is what caused Congress to unanimously pass the Wild Horse and Burro Act,” she said.

The new proposal advocates roundups in densely populated areas that cannot sustain large numbers of animals. It also would move horses currently in short-term holding pens to larger “cost effective, humane” pastures.