Alan Bersin, commissioner of Customs and Border Protection (CBP), said yesterday he plans to resign effective Dec. 30.

David Aguilar, deputy commissioner of CBP, will serve as the acting commissioner until a successor for Bersin is found. Thomas Winkowski, assistant commissioner for the Office of Field Operations, will serve as acting deputy commissioner of CBP.

No reason was given for Bersin’s surprising and imminent departure.

In separate statements, Homeland Security Secretary Janet Napolitano and Senate Homeland Security and Governmental Affairs Committee Chairman Joseph Lieberman (I/D-Conn.) praised Bersin’s leadership at CBP. Lieberman pointed out that Bersin, who was nominated to lead the agency in Sept. 2009, was never reported out by the Senate Finance Committee to have his nomination voted on by the Senate.

Lieberman urged President Obama to move quickly to nominate a successor to Bersin.