The short version is that Harris decided to run only slightly to the right of Sen. Bernie Sanders even though there was a much bigger opening for her just to the left of Joe Biden. That decision has come back to haunt her. With Sen. Elizabeth Warren and Sanders commanding the support of extremely liberal voters, Harris has nowhere to go. It did not have to be this way.
When Harris became a senator in January 2017, despite having been involved in California politics for over two decades as a prosecutor, her positions on many national issues remained undefined. Knowing that she was going to seek the presidency in 2020, it would have been perfectly plausible for her to position herself as a more traditional liberal.
Instead, she decided that her path to the presidency involved joining the stampede of presidential wannabes in the race to the far Left. This led her to be handcuffed into taking radical positions that she wasn’t prepared to defend. And with every equivocation and adjustment, she ended up alienating both sides by developing a reputation of being cynical and calculating.