Washington (CNN) If you asked any smart Democrats on June 28 who they believed, in their hearts of hearts, would be the 2020 Democratic presidential nominee, 9 in 10 would have said Kamala Harris.

The senator from California was coming off a star turn in the first debate of the Democratic primary campaign -- telling her personal story powerfully even while effectively exposing Joe Biden's weakness over his record on busing. She was in command, comfortable on the stage, presidential.

Now, just 83 days later, Harris is fighting for her political life -- pushing all of her political chips into Iowa on the chance that a stronger-than-expected showing in the first caucus is the one thing that can remedy what ails her. " Kamala Harris plots Iowa blitz as campaign stalls ," reads CNN's headline on Harris' all-in-on-Iowa move -- not exactly the headline you want to begin said blitz.

So what happened? How did Harris go from the clear alternative to front-running Biden in late June to needing to make a drastic strategy change to stay relevant in mid-September?

The answer is this: No one thing happened. A confluence of things happened.

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