The #1 weakness of Republican incumbents is the image that they cannot get anything done.
The #1 reason for this is the lack of Senate up or down votes on appointments. If McConnell wants to protect his incumbents he must immediately get 2 up and down votes.
One on executive department appointments.
One on Judicial appointments.
That will do more for McConnell’s incumbents than millions of dollars in donations. The image is reality and McConnell cannot change it. The image is that McConnell and Republican Congress cannot get anything done.
Like P.J. O'Rourke says, "Republicans are the party that says that government doesn't work.....then they get elected and prove it."