I've noticed him signalling to Bernie voters for the past several days. He talks about how things are just as bad on the D side... how Bernie keeps winning state after state, but pundits say, "He can't win."
This "unfairness" aspect will resonate with some of those Bernie people who just want to shake up the system, especially the third or so of them who say they'll never vote for Hillary.
His tweeted support of the Colorado protest is aimed at a wider audience that just the GOPe. "Fighting the system that cheats voters" through demonstrations is an appeal to the Bernie clan.
We'll see if this continues in the next several weeks.
Sounds like a plan.