Bolden flew four shuttle missions. Photo: NASA

The following is a statement by NASA Administrator Sean O'Keefe after being advised of a White House decision to withdraw the nomination of Major General Charles F. Bolden, U.S. Marine Corps, as the agency's next Deputy Administrator.

"We are disappointed that General Bolden isn't able to join NASA at this time. His impeccable credentials as an astronaut and military aviator made him an excellent selection. However, at this critical juncture in our nation's history, we must understand how vital it is for America to focus all its military resources on the immediate national security imperatives.

"Senior military leaders of General Bolden's caliber are a rare and precious resource. The Marines are very fortunate to be able to keep him among their ranks. Given the ongoing war on terrorism and the imperative expressed by the Secretary of Defense that all uniformed military personnel serve to advance the President's objectives to win the war, we fully support the President's decision."

Bolden, 55, currently serves as the Commanding General, 3rd Marine Aircraft Wing in San Diego.

As a NASA astronaut, Bolden piloted Space Shuttles on STS-61C in 1986 and STS-31 in 1990. He commanded two missions, STS-45 in 1992 and STS-60 in 1994. Over the course of his four space flights, Bolden logged more than 680 hours in orbit, assisted in deploying the Hubble Space Telescope and commanded the first mission that included a Russian cosmonaut.