It isn't clear to me that policies are the issue and reason why Democrats lost. For the following reasons:
1. When doing blind studies Americans preferred Harris's policies.
2. In certain states, like Colorado, where the same or even more left-wing policies were messaged differently (framed as saving Americans money overall) Democrats over-performed.
3. We are seeing an anti-incumbency wave globally caused by inflation. Democrats were fighting an up-hill battle to win this election, being the incumbent party. They actually fared better than other incumbent parties globally, containing a lot of their losses. We already know that many working class people voted only on the presidential ticket for Trump for this single reason. That's why Democrats did relatively better in some of the down-ballot races than they did for the presidential election. See: Michigan, Wisconsin, Arizona, Nevada, and maybe even Pennsylvania (depending on how the last few counts and recount goes.)
For the first time since WWII, every governing party facing election in a developed country this year lost vote share, via @jburnmurdoch
— Derek Thompson (@DKThomp) November 7, 2024
2024 Democrats are the red dot.
Absolutely critical context to any postmortem. pic.twitter.com/N6a6L0Pou8
4. In many states that rejected Democrats, progressive referendum showed majority support for their policies. For example, in Missouri a minimum wage of 15 dollars and an abortion protection amendment passed. In Florida a majority voted to legalize recreational marijuana and for a pro-abortion amendment, it didn't pass because the state requires 60% of the vote and the votes were in the low and high 50% respectively. In Arizona a pro-abortion amendment passed.
5. This election wasn't even about policy. Mid-term elections are the policy elections and Democrats have been doing much better in those lately. Neither candidate really talked too much about their policies, and the popular ones were adopted by both.
Trump probably won this election for three main reasons: 1. inflation and the anti-incumbency wave across the globe caused by it, 2. he is charismatic and does better than the average GOP, people like his authoritarian brashness and anti-establishment pose, and 3. Harris focused too much on trying to secure the vote of a group that doesn't exist anymore (Bush Republicans/Neocons) rather than activating her base.
She didn't lose because she is a woman or because she is a person of color either. Many women and people of color in the swing states out-performed her. Yes that is another thing that limits her ability to gather votes, but if #1, #2, and #3 didn't exist she probably would have won despite this.
Edit: Also, Biden shouldn't have run in the first place. He ran in 2020 on being a one-term president and should have stuck with that. There should have been a primary last year.