WASHINGTON — President Obama plans to nominate Jeh C. Johnson, who framed many of the administration’s national security policies as the Defense Department’s general counsel during Mr. Obama’s first term, to become the next secretary of the Homeland Security Department, according to administration officials.

If confirmed by the Senate, Mr. Johnson, 56, will fill the vacancy left by Janet Napolitano, who resigned in July to lead the University of California system.

Mr. Johnson — whose first name is pronounced “Jay” — has little experience with some of the issues that Ms. Napolitano faced, like border security and immigration. But he was a legal adviser to Mr. Obama during his first presidential campaign and has similar views to the president’s about the future of the United States’ counterterrorism operations. He was at the center of Mr. Obama’s first-term efforts to re-evaluate the counterterrorism policies of President George W. Bush.

During his tenure at the Defense Department, Mr. Johnson shaped the Obama administration’s policies on the detention of terrorism suspects and on targeted drone strikes in Yemen and Somalia. He also helped lead the drive to end the “don’t ask, don’t tell” law that had barred gay men and lesbians from serving openly in the military.