Any chance a conservative Independent candidate runs and gains traction?
The Trump comparisons will be way too large to overcome. MA conservatives will be happy to have any Republican in office. Baker is too popular for a non-Democrat to even consider wasting their time with a run.
An independent conservative may be the only way a Democrat can defeat Baker.
Democrats have their work cut out for them trying to defeat Baker, but it won't be due to an independent conservative run. The only way Democrats can defeat Baker is by channeling their anti-Trump energy. Progressive energy in MA is at a fever pitch. The Democratic nominee will need to channel that energy. They need to rack up the margins in the greater Boston area and Western Mass. Despite Baker's popularity his type are the first to go in wave election years.
I might not know Massachusetts politics as you, so correct me if I'm wrong. To me, Charlie Baker looks a lot like where Jodi Rell in Connecticut was before the 2006 election. She had around a 70% approval rating, and was reelected in a landslide. Plus, Conneceticut, like Massachusetts, loves their moderate Republican governors.