The Montana Highway Patrol reported that Judd had drifted into the median, which caused the motorcycle to fishtail, flip and roll. Judd, who was not wearing a helmet, was thrown from the bike and suffered severe head injuries.
Judd was in Montana participating in the International Association of Fire Fighters motorcycle rally in Butte. Judd also was vice chairman of the Utah Democratic Party.
"He is one of the best labor leaders I've come across," Cox said, adding that his care for others underscored his decision long ago to be registered as an organ donor.
Gov. Gary Herbert said Friday in a prepared: "Today the state lost a defender of families and our workforce ... While we are grieved by this sudden and tragic loss, we recognize his lengthy service and good heart benefited many statewide."
Judd served as vice president of the AFL-CIO and became president in 2007 when then-president Ed Mayne, who also was a state senator, died of cancer.
Wayne Holland, an international staff representative for the United Steelworkers in Utah and portions of nearby states, said Judd loved motorcycles and participating in charity rides with union members. "It's just a tragedy for all of us," he said Thursday upon hearing that Judd was on life support.
Judd became involved in the labor movement in Las Vegas in the 1970s when he joined the Teamsters. He moved to Utah in 1977 and went to work for the Ogden City Fire Department, where he became a member of the Professional Fire Fighters of Utah Local 1654. He was elected local vice president in 1978 and became president the next year.
AFL-CIO President Richard Trumka called Judd "a true champion of working people in Utah and around the country who was never afraid to get his hands dirty.
"Jim was perhaps best known in Utah for being a consensus builder who always reached across the aisle and worked towards policies to make working people's lives better. His passion and commitment will live on through his work and the countless people he helped. Our thoughts and prayers are with his family in this very challenging time."
Democratic U.S. Senate candidate Scott Howell, former Utah Senate minority leader, said his party would mourn Judd.
"Jim was a dear friend to me for many years," Howell said in a prepared statement. "I will never forget his sense of humor, his quiet demeanor and his wise advice. I cannot imagine this state, or the state Capitol, without him. This is a very sad time for Utah Democrats."