While the United States prepares to vote in the presidential elections, the current administration is doing the groundwork on post-START arrangement. As I understand, the administration adopted a dual-track approach.
First, it is making the steps that would allow extension of the START Treaty - the next meeting of the Joint Compliance and Inspection Commission (in November?) will have extension of START on the agenda, which is supposed to satisfy the treaty requirement that the sides discuss the extension at least one year before expiration of the treaty.
At the same time, the United States prepared a draft of a new agreement, which is supposed to replace START. The draft is a compromise between a "SORT-plus", suggested by DoD, and a longer 100-page document prepared by the State Department - it is said to be about 60 pages long.