What the hell are the "purists"?
You know them as "conservatives."
Those who are looking for and claim that they will only vote for someone with whom they agree 99.99999999999999999999999% of the time. Usually, such a candidate doesn't exist, so they settle for one slightly less appealing, who comes in at 97.9999999999999999999999999999999999999999999999999999999% on their scale, but has absolutely NO chance of ever winning an election.