Hot take- Sanders not endorsing Markey is a positive. If we make this primary "Bernie vs moderates" we will lose
I think this could be true in the sense that Sanders wasn't that popular in the Boston suburbs in the 2016/2020 primaries, and Markey needs to do well in a good chunk of them to win the primary on September 1. Sanders' endorsement could hurt Markey in the suburbs and potentially drive some Warren-voting 2020 primary Democrats and Markey-supporting moderates in these areas to vote for Kennedy, potentially tipping the election to Kennedy altogether. Then again, I might be reading way too much into this lol.