Third party, spoiler candidates, split ticket, mean Democrat victory about 95% of the time that they appear on the ballot.
Yes, John Anderson tried & failed to derail Reagan in 1980. But Ross Perot succeeded in 1992 against GHW Bush.
Not to make too big a deal about it, but if it wasn’t for Ralph Nader taking 6% (?) of the Florida vote, we would have had President Gore. Works both ways.