There could also be an outside political rationale behind slowing Kerry's announcement. If Kerry is tapped to lead the State Department and the rumored nomination of former Sen. Chuck HagelChuck HagelSpy agencies changed rules, making it easier to unmask members of Congress Pentagon withholding nuclear weapons inspection results: report Lobbying World MORE (R-Neb.) to head the Defense Department pans out, there could be intensified pressure for the president to appoint a female or minority nominee to a top national security position. 

Obama is likely to make such a nomination for director of the Central Intelligence Agency, with former Rep. Jane Harman (D-Calif.) or former Under Secretary of Defense for Policy Michele Flournoy reportedly under consideration. CIA Director David Petraeus resigned last month after an FBI investigation revealed he had an extramarital affair with his biographer.

Last week, White House press secretary Jay Carney acknowledged that the president placed a premium on diversity while at the same time noting that Susan Rice remained in the Cabinet.

"I think the president has always believed to achieve the highest level of excellence in his Cabinet, and more broadly his administration, diversity is important," Carney said.