WASHINGTON (CNN) -- President Bush's deputy national security adviser, J.D. Crouch, is stepping down from his post, the White House announced Friday.

Crouch has worked as deputy to Bush's national security adviser, Stephen Hadley, for more than two years.

His reasons for leaving and when his last day will be were not immediately announced.

White House spokeswoman Dana Perino told reporters Friday there was no set time frame for finding a replacement for him. She later added, "We are not short on people in the administration who can fill positions like that and Steve Hadley is going to work to do that."

In a statement released Friday, Bush said Crouch "was at the forefront in devising and implementing the new strategy to help build a peaceful, stable and secure Iraq."

"He was instrumental in developing the new national security strategy that charts a course for advancing our interests abroad, enhancing global security and liberty, and protecting the American people," the president said.