State Department Counselor Thomas A. Shannon, a former US ambassador to Brazil, is expected to be tapped to succeed Wendy Sherman as Under Secretary of State for Political Affairs, two US officials told Al-Monitor May 28.

Shannon, a career diplomat who previously served as Assistant Secretary of State for Western Hemisphere Affairs, has served as counselor to Secretary of State John Kerry since late 2013. He did not immediately respond to a query from Al-Monitor.

A veteran diplomat focused especially on Latin America, it is not clear if Shannon would take on the Iran nuclear negotiations portfolio that Sherman and her predecessor Bill Burns dealt with in the job, the #3 position at the State Department. It may depend on what stage the Iran deal, or negotiations, are in, one official said.

Negotiators from Iran and the five permanent members ​of the UN Security Council plus Germany (P5+1) are currently meeting in Vienna as they work to finish drafting the comprehensive Iran nuclear accord by the June 30 deadline. Diplomats said this week that progress in drafting the accord has been quite slow since the reaching of a framework deal in Lausanne April 2.