We’ve asked the State Department who will be designated as Acting Secretary of State in the event that Mr. Tillerson does not get confirmation immediately after inauguration day. The State Department directed us to Executive Order 13251 of December 28, 2001 which designates the order of succession for the agency. Based on this E.O., if the Senate drags the confirmation of Mr. Tillerson for months, the State Department will have the Under Secretary for Political Affairs, Thomas A. Shannon, Jr. as Acting Secretary of State until such time when the Senate can confirm the 69th Secretary of State. In the event that Ambassador Shannon is not able to, the next in line is the Under Secretary for Management, Patrick F. Kennedy.
For those of you who follow Latin America, you know that Tom Shannon is an experienced and respected diplomat who worked both for George W. Bush and Barack Obama. In recent times he's been the administration liaison with Venezuela--I most recently wrote about this in November.
The odd thing, then, is that the potential acting Secretary of State is very well qualified but (almost precisely because he is so well qualified as a diplomat) has a mindset that is wholly different from the president he would serve. I have no idea how likely this entire scenario is, but he'd be a good choice, especially for relations with Latin America.