Former Republican Sen. Chuck Hagel is likely to be President Barack Obama's next pick for Secretary of Defense, although the White House has yet to finalize its decision for the cabinet appointment.

A former Pentagon official tells NBC News that Hagel is the likely pick for the post, while another White House insider says that, while Hagel is a top candidate, it's unclear if the president has made a final decision.

A senior administration official tells NBC News that "no decision" has been made on the nomination.

Bloomberg News reported Thursday that President Barack Obama spoke to Hagel about the position on December 4.

Hagel, who served two terms in the United States Senate representing his home state of Nebraska, has been a member of the president's Foreign Intelligence Advisory Board as well as a member of the faculty of Georgetown University since leaving Capitol Hill in 2009.

He also accompanied then-Senator Obama on his campaign trip to Afghanistan, Iraq and the Middle East in the summer of 2008.

While in the Senate, he was a member of four Senate committees, including the Committee on Foreign Relations and the Select Committee on Intelligence.

NBC's Carrie Dann contributed to this report.