He just keeps winning primaries.
What would be a real hoot is if he actually went into the Convention with more votes garnered by actually winning, but lost the Dem's nomination because the the Party's Super Hacks went with Hillary.
Just my opinion, I think his master plan is to wait until the FBI recommends indicting Hillary, and he will be sitting there with all of those delegates, forcing the Party to nominate a man who is a socialist, and NOT a Democrat.
Trump's taking notice. It's now "Crazy Bernie".