I mean the popular support isn't there but they'd in reality only need the support of the texas national guard. A traitor president also helps.
And you also have a ton of people who go "who cares, let them leave" like they're breaking up with a romantic partner lol, absolutley no sense of patriotism.
I mean, I don't care if it is texas, missisipi or claifornia, I am an american and all of it is mine. Whether it is a buch of small skirmishes or a full on civil war again, sececession can only be accomplished by a lot of blood spilled. I can't stand guns and I don't even care enough about politics to vote but if any state tries to secede, I would join whatever military opposing them or just buy a gun and find a secessionist armed soldier to kill and hope that I have a death as honorable as fighting to defend your homeland, sure bests rotting in a bed or in a hospital. Even if I can't get others to join me I can contribute just my tiny drop of blood to the price that needs to be paid to separate a land from its people.
Now, there is exactly one scenario where I'd have no opposition to them seceding: if the constitution is changed to get rid of the electoral college, senatorial representation or if religious rights are infringed upon (even by a SCOTUS decision), and I don't mean protections for miniorities who disagree with a religion but anything that prevents people from sincerely believing (not satanists whose belief according to themselves is fake! For example) in a creator and acting on that belief (including voting). Because before you are a citizen you are a human and before you have legal rights you have natural rights that supersede legal rights(see: declararion of independence) which were the foundation and reasoning used to justify America's secession from Britain.
For Texas secessionists though, all they can acheive is destabilization of the US and as a result the whole world. Russia and China's wet dream but my take on it is that secession is as realistic as a neo-nazi white nationalist state.