washington president donald trump friday nominate columbia university law professor robert jackson advocate public disclosure political spend company vacant seat five-member u.s. securities exchange commission nomination approve u.s. congress jackson would fill spot reserve democrat nomination announce white house statement follow july decision trump tap hester peirce former congressional aide republican seat commission approval nominees would bring agency task police write rule wall street full strength clear way sec chairman jay clayton push ahead agenda reduce regulatory burden public company jackson know advocacy work try advance new rule sec would force public company disclose political spend investors trump nominate columbia professor jackson seat sec