U.S. President Barack Obama, introduces Jeh Johnson (R) as his nominee to be the next Secretary of the Department of Homeland Security, while U.S. Vice President Joe Biden looks on in the Rose Garden of the White House, October 18, 2013 in Washington, DC. The Department of Homeland Security has been without a Senate-confirmed leader for six weeks. (Photo by Drew Angerer/Getty Images)

President Barack Obama says that Jeh Johnson, the former Pentagon lawyer he's nominated to lead the Department of Homeland Security, is an outstanding public servant whom he has known and trusted for years.

"From the moment that I took office, Jeh was an absolutely critical member of my national security team, and he demonstrated again and again the qualities that will make him a strong Secretary of Homeland Security," Obama said.

If confirmed by the Senate, Johnson would succeed Janet Napolitano, who is now president of the University of California system. Obama says Johnson has a deep understanding of the threats and challenges facing the United States.