Carol Vogel called the relevant parties in the choice of art for the White House and got these quotes. Michael Smith is the celebrity decorator who works with the first couple and Harry Cooper is the National Gallery’s curator or Contemporary art:

“We have one rule: We won’t take anything off public display,” Mr. Cooper said in a telephone interview. Nor will the museum lend a work likely to be requested for an exhibition anytime soon. “That limited us to looking at things in storage,” Mr. Cooper added. “But there’s quite a bit.”

Mr. Smith, working with Michelle Obama and the White House curator, William Allman, made choices for the first family’s living quarters and office areas after perusing the Web sites of three Washington museums: the Smithsonian American Art Museum, the National Gallery of Art and the Hirshhorn Museum and Sculpture Garden.

“Michael Smith came to us with a long list of artists and asked me what was available,” Kerry Brougher, chief curator at the Hirshhorn Museum, said in a telephone interview. “There are some very interesting figures. It’s more interesting and shows a greater diversity of art than I’ve seen.”

A Bold and Modern White House (New York Times)