To use a baseball term, you need a "bench" in politics, i.e., people coming up the ranks to bigger and better things in the Political Show. The Republicans cleaned out the Democrats' bench in 2010 and 2014. Now the Democrats are dipping down into their single-A minor league farm clubs to come up with presidential candidates.
This explains the gay mayor of a small city in Indiana, the failed senatorial candidate from Texas, the senile former vice president, the fake Indian, the failed mayor of the nation's largest city, and the California senator-of-color who takes pride in imprisoning her own people. The Democrats are scraping the bottom of the barrel.