Speculation is rife as to who will succeed Hillary Clinton as US secretary of state after she steps down in January.

US President Barack Obama's pick for the post, US Ambassador to the United Nations Susan Rice, has come under fire from Republicans who claim that Rice and the Obama administration deliberately concealed information about the attack on the US consulate in Benghazi, Libya, for political gain ahead of the presidential election.

Rice was the public face of the Obama administration when it initially blamed the attack on demonstrations against an Internet video defaming Islam's Prophet Muhammad. The administration later confirmed it was a terrorist attack.