Congress and the president can undo any law or act with a simple majority. The only bills passed that cannot be undone in such a way are Constitutional requirements. Or so that is how I understand it to be.
All the rest is bluster by the idiots who passed the initial law.
In place of “bills,” I meant “actions.”. Overriding a veto, for instance, still requires 2/3 of both Houses, etc.
When, in the course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the laws of nature and of nature’s God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.