The Missing Obama Millions:
...many analysts see Romney voters who flipped to Mrs. Clinton as an illustration of how the Democratic Party now survives in significant part by appealing to more upscale voters.
Frustratingly, however, these perspectives play down the importance of a crucial group of disaffected voters: those who voted for Mr. Obama in 2012 but then failed to go to the polls in 2016. Because this group is disproportionately young and black, this erasure is racially tinged.
Obama-to-nonvoters share the progressive policy priorities of Democrats, and they strongly identify with the Democratic Party. Four out of every five Obama-to-nonvoters identify as Democrats, and 83 percent reported they would have voted for a Democrat down-ballot. A similar share of Obama-to-nonvoters said that they would have voted for Mrs. Clinton had they turned out to vote. In short, while reclaiming some Obama-to-Trump voters would be a big help to Democratic prospects, re-energizing 2012 Obama voters who stayed home is a more plausible path for the party going forward.
Whether Democrats can mobilize these voters is an open question, however. Significantly, only 43 percent of Obama-to-nonvoters reported being contacted by a candidate in 2016, compared with 66 percent of Obama-to-Clinton voters. While analysts have focused on why many conservative voters switched to the Republican Party, a better question might be why a campaign that sought to energize young voters of color failed to do so.
The study did some analysis of policy preferences for these voters, but it seems to have just been a kind of baseline comparison to confirm that they are "liberals" and not conservatives. It would have been nice to see if the more progressive policies of a Bernie Sanders type candidate might have motivated them more than Clinton's platform. My theory is that is certainly wouldn't have hurt, and it also might have peeled off a lot of the third party voters.