fwiw, amending the US constitution generally requires a 2/3 majority in both houses of congress to propose the amendment, and then further ratification by 3/4 of the states make the amendment law. it's a fairly long process, and amendments sometime get bogged down and die in the 2nd phase.

(there is another process which calls for a convention, but such a convention would have broad powers to change many things and so far the "two sides" (US rules tilt toward two parties rather than more) have been too scared of what might happen to do that)