Scott made the decision early in the cycle to abandon the tactics of his predecessors and maintain a hands-off posture during the primaries. That approach, Republicans privately complained, ended up hurting some candidates -- particularly in Ohio and Arizona -- as they pivoted to the general election from the primary. Since some lacked candidate training, access to critical research and experienced staff and fundraisers that the NRSC has given candidates in previous cycles, it provided well-funded Democratic candidates a chance to bombard the airwaves while their GOP opponents were still finding their general election footing. The NRSC has said that it has worked closely with various candidates and will do what is necessary to win in November.

In past election cycles, McConnell was heavily involved in the NRSC. But as his disagreements with Scott's approach intensified, he has instead focused his efforts squarely on his super PAC.

"McConnell decided rather than fight this to focus all his efforts on SLF," a source familiar with the matter said.