Josh Marshall distills the lie at the core of the nuclear option:
(Just to be crystal clear, what the senate is about to do is not changing their rules. They are about to find that their existing rules are unconstitutional, thus getting around the established procedures by which senate rules can be changed.)
Their reasoning will be that the federal constitution requires that the president makes such nominations “by and with the Advice and Consent of the Senate” and that means an up or down vote by the full senate.
You can think the filibuster is a terrible idea. And you may think that it should be abolished, as indeed it can be through the rules of the senate. And there are decent arguments to made on that count. But to assert that it is unconstitutional because each judge does not get an up or down vote by the entire senate you have to hold that the United States senate has been in more or less constant violation of the constitution for more than two centuries.
For all the chaos and storm caused by this debate, and all that is likely to follow it, don’t forget that the all of this will be done by fifty Republican senators quite knowingly invoking a demonstrably false claim of constitutionality to achieve something they couldn’t manage by following the rules.