28 CFR §51.43

1. (a)After notification to the submitting authority of a decision not to interpose an objection to a submitted change affecting voting has been given, the Attorney General may reexamine the submission if, prior to the expiration of the 60-day period, information comes to the attention of the Attorney General that would otherwise require objection in accordance with section 5.
2. (b)In such circumstances, the Attorney General may by letter withdraw his decision not to interpose an objection and may by letter interpose an objection provisionally, in accordance with § 51.44, and advise the submitting authority that examination of the change in light of the newly raised issues will continue and that a final decision will be rendered as soon as possible.