If NJ-SEN 2018 didn’t teach people how much the supposed unpopularity of blue state Democrats actually matters in a general election, then I don’t think anything will. It’s possible/likely that he’s more unpopular than that, but this race is titanium D regardless of who the Democrats (or Republicans) run, as is CA.
I'm not sure it's comparable. As gross as I find Menendez, I could stomach voting for him because it directly effected something greater. If Menendez were governor however, I'd probably vote for the Republican.