Democrats have been funding the most extremist and crazy of their opponents in political races for years now because it's a lot easier to run on the policy of "At least I'm not that guy" than it is to actually convince people to vote for you based on your policies and agenda. Hell, some lady wrote a book about how she did it to win a seat, only to lose to that same guy in the very next election.
It's one of the oldest and most effective campaign strategies there is, but it keeps biting Democrats in the ass and they keep trying it anyways. Democrats seem to think that moderate Republicans will vote for them over the extremist candidate, but Republicans don't care about who the candidate is so long as they're a Republican.