The establishment in Alabama hated Moore and would not back him. Additionally, Richard Shelby got on National television and urged Alabamians to "write in" some other name.
Something like 23,000 "write in" ballots occurred, which broke the record in Alabama.
Having the other US Senator from Alabama urge his own voters not to support Moore is a stab in the back that is hard to recover from.
Moore almost managed it anyway. I think if the fraud was thrown out, he probably would have won.
Too risky!
The Senate seat is too important.