There was a bit of sniping on the conservative side of things that the Democratic Party was out for ideological purity, not popular candidates. Which may be true. But, at least we try to get candidates we don't like out during a public election.
The Republican Party tries to fight them off even before they get on the ballot. Seattle Times in 2005:
But state Republicans also adopted rules for a Montana primary — rules state GOP Chairman Chris Vance says are now in effect — that assert the party's "right to grant permission to use the Republican name ... only to candidates who demonstrate significant support within the Republican Party."
In most cases, the rules require a candidate to have received 25 percent of the vote at the county convention. Candidates also could have qualified by submitting to the party by last Friday a large number of voter signatures, but Vance said he knew of no candidates taking that route.
Democrats have adopted no similar rules.