(a) After consideration of all relevant information which has been presented, the Assistant Secretary shall issue a decision on the continuation or revocation of the affirmative 18(e) determination.

(b) The decision revoking the determination shall also reflect the Assistant Secretary's determination that concurrent Federal enforcement and standards authority will be reinstated within the State for a reasonable time until he has withdrawn his approval of the plan, or any separable portion thereof, pursuant to part 1955 of this chapter or he has determined that the State has met the criteria for an 18(e) determination pursuant to the applicable procedures of this subpart.