Be serious, those like McConnell will not even get a serious primary challenger. Collins has been there as long as she has because Maine wants her there. A practical goal might be to replace a few like Sasse with more reliable conservatives. He votes with Trump 80% of the time but Nebraskans don’t like his showboating. McSally will run as an incumbent and is as conservative as you can expect to get from the state that reelected McTurd over and over.
He had a very good challenger last time, KY elected him Gov.