A lot of Sanders voters didn’t even get to vote in the primary (especially in Cali and NY), or his totals would have been even higher.Democrats tend to be more emotional. If you slight "their" guy, I think you end up with more of the same as 2016. I believe there were a lot of Sanders voters that felt so betrayed by the DNC nominee process that their vote, if they voted, converted to "anyone but Clinton."
Poll: 1 in 4 Sanders supporters won't vote for Clinton
Wikipedia page for 2016 DNC primaries
13,206,428 Votes for Sanders in the various Democratic primaries. If 25% of those people really didn't vote for Clinton, that's 3,301,607 votes that she missed out on. I don't have any way of determining just how those people polled, actually voted in the presidential race, that would have pushed Clinton's popular vote total up another 3M for a total of 6M above Trump.
Take a look at Michigan: 598,943 votes for Sanders. 25% of that is 149,735. Hillary lost Michigan by only 10,704 votes.
I imagine you could find a trend for many of the states she lost that she considered a lock.
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