Bob Workman announced Monday that he has resigned as executive director of Crystal Bridges Museum of American Art.
Workman will continue to work with the museum in Bentonville, which is still under construction, until the end of 2009.
Workman said he decided to leave because he could not make a commitment to stay beyond the museum opening, according to a news release.
The museum was originally slated to open this year but construction has been slowed because of the unique site and scope of the building.
"I accept Bob's resignation with regret, understanding and gratitude," Alice Walton said in a news release. Walton, heir to Wal-Mart Stores founder Sam Walton, has spearheaded the museum and will seed it with her extensive private art collection.
"He has done a magnificent job and will be leaving a beautiful legacy. Crystal Bridges wouldn't be what it is without Bob. I am pleased he will continue to work with us and deeply grateful for the innumerable contributions he has made."
Workman became executive director of the museum on Jan. 1, 2006. He was the deputy director of the Amon Carter Museum in Ft. Worth for nine years prior to joining Crystal Bridges.
The museum has said it will conduct a national search for a new executive director.
The $50 million Crystal Bridges, founded by the only daughter of Wal-Mart founder Sam Walton and set on 100 acres of Walton family land, will house American masterworks. The works, bought by Alice Walton and the Walton Family Foundation, include "Kindred Spirits" by Asher B. Durand, considered one of the finest examples of the Hudson River School and for which Walton reportedly paid more than $35 million. Also: Thomas Eakins' "Portrait of Professor Benjamin H. Rand"; paintings of George Washington by Gilbert Stuart and Charles Willson Peale; and Winslow Homer's "Spring."
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