U.S. Sen. John Kerry, D-Mass., whom President Barack Obama recently nominated to be the next secretary of state, is testifying in a confirmation hearing Thursday in the Senate. Reuters

Sen. John F. Kerry (D-Mass.) is being considered by President Barack Obama to become the nation's next defense secretary, senior administration officials, familiar with the cabinet transition, told the Washington Post.

Kerry had been said to covet Hillary Clinton's job as Secretary of State, but that position is almost certain to go to Susan E. Rice, who is currently the U.S. ambassador to the United Nations, administration officials, who spoke on condition of anonmity, told the newspaper. Clinton is stepping down at a time when several key issues, including the status of Iran's nuclear weapons program and an increasingly violent war in Syria, remain unresolved.

Several other Obama officials, including treasury secretary Timothy Geithner, attorney general Eric Holder and press secretary Jim Carney, have also announced plans to step down, either this year or next year. The departures come as Washington is facing a big fiscal crisis, among other challenges.

Defense Secretary Leon Panetta said on Monday that he had no immediate plans of stepping down, adding, however, that he was unlikely to remain in the job for the duration of Obama's second term.

It’s no secret that at some point I’d like to get back to California,” Panetta said earlier this week.

While Kerry's camp has remained mum on his potential nomination, some administration officials said that his foreign service record, in addition to his budgetary and diplomatic knowledge, would make him a well-qualified candidate for secretary of state. The 2004 presidential hopeful won two Purple Hearts during the Vietnam War, and he is the current chairman of the Senate Foreign Relations Committee.

The Democrats retained a Senate majority, gaining two seats in the recent elections, which helped to strengthen their grip and provided the party enough of a cushion for Kerry to depart and join the President's cabinet.

Kerry had been said to covet the Secretary of State job, but that role now seems to be in the hands of Susan E. Rice. She will be grilled by Republican legislators this week amid concerns that she purposely miscast the Benghazi incident as a peaceful demonstration that turned violent, and not as an organized, premeditated attack on the U.S. consulate in Libya. U.S. Ambassador J. Christopher Stevens and three other Americans were killed in the attack.

In spite of the criticism, Obama, officials have said, want Rice as secretary of state and is expected to fight for her, if need be.

Obama must also tap a successor to former C.I.A. head David Petraeus, who stepped down earlier this week after admitting to an extramartial affair with his biographer, Paula Broadwell. John O. Brennan, Obama's counterterrorism adviser, is said to be the leading candidate to run the C.I.A.