U.N. Ambassador Susan Rice has announced that she will not be a candidate for Secretary of State in the second Obama administration. It is likely she wrote the letter taking her name out of contention at the direction of the White House.
The immediate credit for pushing her out of contention goes to a group of Republican Senators. Those Senators' opposition can be credited to the new media which has taken a extraordinarily dim view of Rice's testimony concerning the debacle at the U.S. consulate in Benghazi, Libya.
In that testimony Rice repeated the White House talking points concerning the causes of that attack when she either knew, or should have known, that the talking points were counterfactual, that is to say, untrue.