Time Magazine has an story outlining the five big mistakes the Hillary ClintonHillary Diane Rodham ClintonRepublican Ohio Senate candidate slams JD Vance over previous Trump comments Budowsky: Why GOP donors flock to Manchin and Sinema Countering the ongoing Republican delusion MORE campaign made to end up where it is today. One of them, according to Time, was that she trusted Mark Penn who reportedly thought the proportional Democratic primary system was actually a winner take all system. On that assumption Penn thought Clinton would secure the nomination after winning California and each of the states 370 delegate's.

From Time's story:
As aides looked over the campaign calendar, chief strategist Mark Penn confidently predicted that an early win in California would put her over the top because she would pick up all the state's 370 delegates. It sounded smart, but as every high school civics student now knows, Penn was wrong: Democrats, unlike the Republicans, apportion their delegates according to vote totals, rather than allowing any state to award them winner-take-all. Sitting nearby, veteran Democratic insider Harold M. Ickes, who had helped write those rules, was horrified