Is Charlie Baker beatable?

Charlie Baker, the most popular governor in America, looks like a lock for reelection, according to polls, pundits, and even lots of Democrats you talk to. But don’t count John Walsh as one of them. The former chairman of the Massachusetts Democratic Party insists Baker can be defeated -- and he says the governor’s team knows it. It explains why, Walsh says, Baker is furiously raising millions of dollars for his campaign -- and bending all sorts of campaign finance rules to do so. Is Walsh onto something, or is he on something?