Hillary Clinton plans to accept the job of secretary of state offered by Barack Obama, who is reaching out to former rivals to build a broad coalition administration, the Guardian has learned.

Obama's advisers have begun looking into Bill Clinton's foundation, which distributes millions of dollars to Africa to help with development, to ensure there is no conflict of interest. But Democrats believe the vetting will be straightforward.

Clinton would be well placed to become the country's dominant voice in foreign affairs, replacing Condoleezza Rice. Since being elected senator for New York, she has specialised in foreign affairs and defence. Although she supported the war in Iraq, she and Obama basically agree on a withdrawal of American troops.