Maybe last night was the last straw for some people... 
If he plans on continuing voting like a right-wing Republican, then there's no reason for Democrats to support him or accept him in their caucus (unless some law says they have to). If he's willing to make some policy concessions -- which he might as well since I'd imagine this term would be his last -- then maybe it doesn't matter. Smaller stakes than the US Congress and all, and the legislature's not flipping.
New Jersey's a machine state, though. Whatever the establishment wants in this state is what they're gonna get.
There's really no reason for Democrats to support him.
Minnesota has a kind of similar story: some guy represented a very ancestrally R (Like >70% for Goldwater) State House district since 1991, (FYI my church is actually there.) He was though more moderate than the rest of the caucus, especially after the 21st century started and most of the moderates retired or were primaried out but never had any trouble. That changed in 2008 when the DFL Legislature successfully managed to override Pawlenty's veto of a transportation funding bill, Pawlenty vetoed it because he opposed the 5-cent a gallon gas tax increase to fund most of its projects even though the gas tax had not been raised in 20 years. The DFL had just short of a supermajority in the House, but five Republicans crossed over to vote for it including him. Well that angered the right and they rallied around his primary challenger.
At the convention he lost the Republican endorsement, and he had pledged to not run for the Republican nomination in the primary if he lost the endorsement, and he held to that...but instead he ran in the general election as a third party (I believe he literally ran under the "Moderate Independent" ticket as a party name), and promised to caucus with the majority. And thus in that 3-way race a hard right Republican was able to get elected in a district that Obama carried by double digits and the DFL won all surrounding districts in a landslide. And then in 2010 said Republican was able to narrowly survive via the GOP wave.
So then came 2012 and the DFL were certain they could take the seat because Obama was obviously going to carry it by a lot...which was correct, but guess who the candidate was? Yep that now former incumbent filed as a Democrat and stupidly the field cleared for him. He won the primary and the general election easily. Keep in mind this guy is now 82 years old, so he really should've just have been enjoying retirement.
In 2014 he did manage to narrowly survive and it was clear voters were sick of him, so he faced a primary challenge in 2016...but the convention voters decided to nominate an 86-year old dinosaur over a 37-year old. And then...he lost! He actually lost to another supposedly "moderate" Republican who to be fair did have a bit of a moderate voting record but still meant another seat in the R caucus. And you got to remember this is with Trump absolutely hitting the floor in this district, in 2012 Romney actually didn't do that bad and had a respectable loss...this guy was representing a district that was like Hillary+18.
Well unsurprisingly he lost in 2018 and the seat flipped to a Democrat who now holds it today, although he probably doesn't mind because afterwards he renounced the GOP and then ran and won for a spot on the Hennepin County Commission that he won and holds now (Hennepin County Commissioners get paid like $130k/year annual salary, while state legislators get in the $40k range...most other counties in the metro pay similarly so county commissions are full of ex-legislators, even mine is a former one-term DFL State Rep from Minneapolis who ran for that job as soon as one opened up.)...but the DFL could've avoided that by simply not dealing with that guy to begin with.
