Michèle Flournoy out of running to be Defense secretary: Top prospects now Washington - Michèle Flournoy has taken herself out of the running to be the next secretary of Defense, a prospect that would have made her the first woman to hold the job. She was widely considered a top pick for the position, having previously served as the Pentagon's undersecretary for policy for former Defense secretaries Robert Gates and Leon Panetta. Ms. Flournoy explained her reasons for the preemptive move in a letter she sent Tuesday to the board of directors at the Center for a New American Security, an influential and relatively new Washington think tank that she cofounded, and where she currently serves as chief executive officer. "Last night I spoke with President Obama and removed myself from consideration due to family concerns," reads the letter, first reported by Foreign Policy (FP) magazine. After much agonizing, we decided that now was not the right time for me to reenter government. In the letter, she explains that family health considerations, as well as the fact that two of her children are soon headed off to college, drove her decision, according to FP. Now the Obama administration must rustle up some other candidates. Sen. Jack Reed (D) of Rhode Island, a former Army Ranger who was also an early possible pick, stressed this week that he is not interested in the job, since he just won his Senate race. The White House is also said to be considering Ashton Carter, who was deputy secretary of Defense from 2011 to 2013. Dr. Carter, who has a doctorate in theoretical physics from Oxford, specializes in the complex world of military procurement: When he was undersecretary of Defense for acquisition from 2009 to 2011, for example, it was his job to sign off on the billions of dollars in new weapons and technology that the Pentagon buys each year. The current secretary of Homeland Security, Jeh Johnson, is another name that has cropped up in the wake of Flournoy's letter. Secretary Johnson was the Pentagon's widely regarded top lawyer before he took the job at Homeland Security. A former New York attorney, Johnson "proved to be the finest lawyer I ever worked with in government - a straightforward, plain-speaking man of great integrity, with common sense to burn and a great sense of humor," former Defense Secretary Gates writes in his memoir. Regardless of Mr. Obama's ultimate choice, what is clear is that the candidate will face a contentious hearing on Capitol Hill. Incoming Senate Armed Services Committee chairman John McCain (R) of Arizona, one of the administration's most vocal critics, will probably turn the confirmation hearing into a referendum on the president's Middle East policies. As a result, confirmation for a new secretary of Defense could take at least a couple of months, a reality that Pentagon officials acknowledge. They note that Secretary Chuck Hagel - who has agreed to stay on the job until his successor is confirmed - has plenty to keep him busy in the meantime. "He's very much focused on implementing the recommendations and changes that he has accepted from the reforms that we put in place - Navy Yard shooting, nuclear enterprise review, medical health system review," Rear Adm. John Kirby, Pentagon press secretary, said Tuesday, adding that addressing sexual assault in the armed forces also tops Secretary Hagel's list. "So it's very much for him about, you know, continuing to keep his foot on the pedal," Rear Admiral Kirby said, "and moving forward."