Undersecretary Asa Hutchinson, in charge of border and transportation security issues, submitted his letter of resignation to the White House early Monday morning, said a DHS official, who spoke on condition of anonymity because the resignation had not yet been announced.
Hutchinson is a former Arkansas congressman and former federal drug czar who is believed to be considering a run for Arkansas governor next year. His resignation is expected to be effective March 1.
"It was just a good time to change for me personally and for the department," Hutchinson told the Arkansas Democrat-Gazette, which first reported his plans.
Earlier this month, President Bush tapped federal appears court judge as his second nominee to head the Homeland Security Department and its 180,000 employees. The president's first choice, former New York City Police Commissioner , withdrew shortly after he was nominated in December, citing immigration problems with a former nanny.
Outgoing Homeland Security Secretary Tom Ridge plans to leave his office Feb. 1.
Hutchinson, 54, has said that he was disappointed that he wasn't selected to be secretary but is excited about other options, including a possible run for Arkansas governor in 2006. But Hutchinson didn't give any definite political plans for the future.
"We'll wait and see," Hutchinson told the newspaper. "I'm ruling nothing out. I'm taking the decision-making process a step at a time."
Hutchinson served three terms in Congress, representing the state's 3rd Congressional District. He served as head of the Drug Enforcement Administration and then in the Department of Homeland Security.