A bill that restores and strengthens protection for wild horses has been passed by the United States House of Representatives.
The Restore Our American Mustang Act, or ROAM Act (HR 1018), passed by a vote of 239 to 185.
It still needs to be passed by the US Senate before it becomes law.
The push for the legislation was led by Natural Resources Committee Chairman Nick Rahall Jun (D-WV), Representative Ed Whitfield (R-KY), and Subcommittee on National Parks, Forests and Public Lands Chairman Raul Grijalva (D-NM)
The Animal Welfare Institute welcomed the passage of the bill.
"At a time when nearly as many wild horses are in captivity as are on the range - a situation which is unacceptable in terms of both animal welfare and fiscal responsibility - the Animal Welfare Institute welcomes this action, and we are grateful to the bill's champions and supporters," said Chris Heyde, Deputy Director of Government and Legal Affairs for the Animal Welfare Institute.
The Bureau of Land Management (BLM) has raised the possibility of euthanizing some of the horses in captivity, or offering them for sale "without limitation", as it faces a budget blow-out over the cost of keeping the animals in captivity.
The new legislation would encourage the reopening of certain public lands to the mustangs, thus potentially decreasing the number in captivity.
The bill also restores a crucial protection to keep wild horses from going to slaughter, which was stripped away several years ago.
"The BLM's wild horse programme and policies are broken," Heyde said. "The ROAM Act offers an opportunity for the agency to restore its credibility when it comes to managing America's mustangs.
"We urge the Senate to act swiftly before the BLM takes further actions of detriment to the horses."
It was not all plain sailing for the bill in the House, with Republican opponnents arguing it showed Democratic priorities were focused on animals instead of people during tough economic times.
About 36,000 wild horses are estimated to roam the western rangelands of the US, just 5000 more than the 30,000 held by the BLM.
In Friday's vote, 206 Democrats supported the measure and 47 opposed it. Among Republicans, 33 voted for it and 138 against.
In March at a legislative hearing on the ROAM Act, Congressman Nick Rahall stated his position in support of the wild horses. "Since 1971, more than 200,000 wild horses and burros have been rounded up from public lands and either adopted or placed in long-term holding facilities," he said.
"And of critical concern, the BLM recently announced that, due to a combination of a lack of funding, facilities and options, they may be required to kill as many as 30,000 healthy wild horses and burros. Let me state that the BLM is not going to slaughter 30,000 wild horses - not under this Chairman."