The Minnesota native earned Hillary Clinton’s trust as an ­adviser to her 2008 presidential campaign, and at the State Department, where he was the youngest-ever director of policy planning. After she left, Sullivan stayed on to see through the Iranian nuclear deal he was instrumental in launching. He rejoined ­Clinton for her second run, expanding his foreign-policy portfolio to include domestic affairs and outreach to businesses. If Clinton wins, look for Sullivan to take a senior White House post, possibly deputy chief of staff.