As I recall, there was a similar situation in 1985 with Senators Helms and Lugar, and Helms pulled seniority on Foreign Relations though Lugar had been the ranking member for the previous two or four years. Helms had been chairing Agriculture but switched to Foreign Relations in 1985. Then he was out as chairman in 1987 because 1986 was a huge Democrat year even before hapless voters knew of Iran-Contra.
Helms was the most honest Senator in my lifetime.