LITTLE ROCK, Ark. (AP) – Lt. Gov. Win Rockefeller, the unassuming billionaire who last year abandoned a race for Arkansas governor – a post once held by his father – died Sunday after unsuccessful treatments for a blood disorder, his office said. He was 57.

Rockefeller died Sunday morning at the University of Arkansas for Medical Sciences with his family present, his spokesman Steve Brawner said.

Bone marrow transplants Oct. 7 and March 29 at Seattle’s Fred Hutchinson Cancer Center failed to cure an unclassified myeloproliferative disorder.

He returned to Arkansas on July 8 and immediately entered the hospital. The next day, Rockefeller notified Gov. Mike Huckabee that he could not continue his duties, at least temporarily.

“Win Rockefeller embodied the ideals of compassion, generosity, and humility. He was a wealthy man, but his real wealth was not his money, but his heart for serving others,” Huckabee said in a statement. The governor cut short a trip to New Orleans for the Southern Governor’s Association meeting to return to Little Rock.

Under the Arkansas constitution, Huckabee does not have the authority to name a replacement to fill the remainder of Rockefeller’s term, which ends in January. Senate President Jim Argue, D-Little Rock, who will direct Arkansas government when Huckabee is out of state.

The great-grandson of Standard Oil founder John D. Rockefeller ranked No. 283 on the Forbes magazine list of the nation’s wealthiest people in 2005, with a fortune the magazine estimated at $1.2 billion. As lieutenant governor, a part-time job, he donated his $34,673 state salary to charity.

Born Sept. 17, 1948, in New York, Rockefeller was the only child of former Gov. Winthrop Rockefeller and Barbara “Bobo” Sears. An uncle was former vice president Nelson Rockefeller, and current U.S. Sen. Jay Rockefeller, D-W.Va., is a cousin.

Winthrop Rockefeller, who served two-year terms beginning in 1966. The father died in 1973 at age 60 of cancer.

The son entered politics in 1996, winning a special election to complete the unexpired lieutenant governor term of Huckabee, who became governor after Jim Guy Tucker was convicted in a fraud case as part of the Whitewater investigation.

Rockefeller won re-election twice, winning 67 percent of the vote in 1998 and 60 percent in 2002. As lieutenant governor, he presided over the state Senate and served as governor when Huckabee was out of the state.

He also served as an economic cheerleader for the state, traveling at his own expense to seek foreign investments here.

Under the state’s term-limits law, he could not serve another term.

Huckabee and Rockefeller had an amiable relationship. The governor appeared to brand Rockefeller as his heir apparent in 2004 when he said voters should vote a GOP ticket in 2006.

“I think people will say, ‘It was a Republican governor who opened health care and the different highway programs; it was a Republican governor who pushed for increased standards in our schools,”‘ Huckabee said.

But that was before former Homeland Security Undersecretary Asa Hutchinson entered the governor’s race. With two Republicans on the ballot, Huckabee was careful not to lean either way.

After his father’s death, Rockefeller bought Winrock Farms Inc., founded by his father in 1953, and became involved in banking, retailing, automobile dealerships and resorts.

Sen. Hillary Rodham Clinton, D-N.Y. and a former Arkansas first lady, noted Rockefeller’s “extraordinary public service” in and out of office.

Rockefeller was a member of the Arkansas State Police Commission from 1981 to 1995 and chairman of the President’s Council on Rural America after his appointment in 1991 by the first President Bush.

Rockefeller supported literacy councils and in 1997 created the Books in the Attic program, in which Boy Scouts collect used books to distribute.

Two of his eight children have Down syndrome, and Rockefeller and his second wife, Lisenne, started what is now the Academy at Riverdale, a school for children with learning disabilities.

Rockefeller also founded The Billfish Foundation, an organization dedicated to protecting marlins, swordfish and other billfish. As a National Rifle Association member, he sponsored Project ChildSafe to distribute free trigger locks in the state.

Survivors include his second wife, his mother, three daughters, five sons, a granddaughter, a stepbrother and a stepsister.