President Barack Obama suffered the fourth high-profile withdrawal of a key nominee on Thursday when Judd Gregg, a Republican senator for New Hampshire, stepped aside as commerce secretary candidate, citing “irresolvable” policy conflicts.

Mr Gregg, who was to be the third Republican in Mr Obama’s cabinet, cited policy differences over the $789bn (£552bn) fiscal stimulus, which remains likely to be passed in the next two days, and on which the senator abstained when it came to a vote this week.