McConnell finds himself increasingly constrained by both his new primary challenger and McCain’s expanded deal-making role with Democrats.

Republican senators told The Hill on Wednesday that McConnell is in danger of looking weak if McCain again seizes the leadership reins as he did to broker a deal to avert the “nuclear option” on President Obama’s executive nominees.

McCain is interested in being a major player in the talks later this year when Congress must pass legislation to continue government funding and raise the national debt limit.

The McConnell-McCain relationship has fluctuated over the years. One GOP aide described it as “toxic” in the late 1990s and early 2000s when they fought intensely over campaign finance reform legislation.