Whenever the Secretary, after affording reasonable notice and an opportunity for a hearing to any State or unit of local government, finds that there has been a failure to comply substantially with any assurance set forth in the statement of assurances of that State or units of local government filed under section 6725 of this title, the Secretary shall notify that State or unit of local government that further payments will not be made under this subchapter until he is satisfied that there is no longer any such failure to comply. Until he is so satisfied, no further payments shall be made under this subchapter.