RENO ? Sheryl Crow has spoken out against the war in Iraq and in support of embryonic stem-cell research and efforts to combat global warming. Now, she’s trying to ride to the rescue of thousands of wild horses that roam the West.

After campaigning for President Barack Obama in 2008, the Grammy-winning singer has become a leading critic of his administration’s plans to remove as many as 25,000 mustangs from the range and ship them to pastures in the Midwest and East.

Since coming out in favor of a moratorium on government roundups of mustangs in November, Crow has lobbied Interior Secretary Ken Salazar, dropped off books and DVDs about wild horses for Obama at the White House and appeared in a video produced by equine activists.

To no avail, she also called on the president to halt a roundup of about 2,500 mustangs in Nevada, which began late last month as part of the administration’s strategy to remove thousands of mustangs from the range.

“My main concern is that horse numbers not be dwindled down to where they can become extinct,” she said, fearing the roundups are leaving mustang herds with too few breeding horses.