The brother of Democratic Sen. Mark Udall of Colorado has been missing since June 26, when he failed to return from a solo hiking trip in Wyoming.

A search is now underway for James Udall, a 61-year-old environmentalist, his daughter, Ren Udall, confirmed to the Post Independent of Glenwood Springs, Colo.

"We're just trying to keep the phones open and do some logistical work from here," she told the paper.

James Udall, known as Randy, is from Carbondale, Colo. His brother, Mark Udall, is a Democratic U.S. Senator from Colorado and his cousin, Tom Udall, is a Democratic U.S. Senator representing New Mexico.

"Mark is concerned about his brother's whereabouts and he continues to closely monitor the situation," Mark Udall's press secretary, James Owens, told a local NBC affiliate in Colorado. "He and his family hope for the best."

A news site in Pinedale, Wyo., near where James Udall disappeared describes him as 6 foot, 4 inches tall, 200 pounds with gray/brown hair and blue eyes. "He was hiking alone in the central Wind River Range from the Elkhart Park trailhead. He is an experienced hiker, familiar with the Wind River Mountains," the site reported.