Moore represents the effort by Steve Bannon, the former Trump advisor, to unseat establishment Republicans, against Mitch McConnell’s will. If Moore exits the race, it’s big blow to Bannon’s efforts.
In the meantime, the GOP could push a write-in candidate or run Moore against Doug Jones, the Democratic candidate. A loss by Moore to Jones wold certainly solve the problem but would leave McConnell with one less Republican seat in the Senate.