This was something passed by a Democratic administration. Therefore Republicans hate it, and since 2/3 of the Supreme Court is Republican, it's likely to be struck down.
The actual reasoning comes later. Something-something-Federalist-Papers-something. I'm sure they'll have no trouble digging up some Founding Father who said something that sounds like banning this, if you squint right.
I know a great many lawyers, of both parties, who have more respect for the Supreme Court than I do. They are more informed and better educated than I am, so you should take my cynicism with a grain of salt. But in my experience, treating the Supreme Court as a partisanship machine yields extremely accurate predictions.
