While I do think he’s an effective bureaucrat and statesman, Newsom is genuinely reviled by California Republicans. Republicans not liking their Democrat governor is obviously nothing new, but there was nowhere near even 1% of the same vitriol being directed towards Jerry Brown, his predecessor and also a Democrat.
I kind of feel like Newsom doesn’t really have the chops for the national stage yet. He doesn’t have any accolades to his name, was mired in a scandal during Covid, and California is not doing so hot on the issues that the Dem establishment are trying hard to tackle. Chiefly among those issues is rampant homelessness and drug addiction, which the state has funneled billions into trying to solve and so far gotten nowhere fast. The attack ads almost write themselves.
To be clear, I do find him appealing (at least more than Biden), but I think he’s going to have an uphill battle at unifying the disparate Democratic party if he’s given 4-ish months to mount a campaign.