CNN cited a Democratic source who had spoken to Kerry, while ABC mentioned unnamed sources. Asked for comment by AFP, the White House did not immediately confirm the reports, but Kerry is seen as a frontrunner for the role. 

The defeated 2004 Democratic presidential candidate, Kerry is currently head of the powerful Senate Foreign Relations committee. 

On Thursday, Obama's ambassador to the United Nations, Susan Rice, withdrew her name from consideration for the secretary of state post, effectively elevating Kerry to the prohibitive favorite. 

Rice had come under fire over controversial statements about the deadly September 11 attack on a US mission in Libya, and some Republican lawmakers had vowed to block her path to becoming top diplomat.