John Roberts can stop Trump, no one else

Who decides whether a president is eligible for office. Congress certainly can on January 6th - but that is not the last possible moment. Anyone with standing can seek an injunction in the DC Federal District Court to stop Trump from being sworn in. Ultimately, it is up to Chief Justice John Roberts to decide if his constitutional oath to protect the Constitution from all enemies, foreign and domestic, includes not swearing Trump in. He can do so the very moment he is to swear in Trump, instead swearing in Vance under the provisions of the 20th Amendment. He could even notify the House Administration Committee of this issue, which would force them to require a 14th Amendment vote for the president-elect to be qualified. Regardless, there is no way that the electoral vote count can be used to elect Kamala Harris as President-elect. The key provision is 20, not 14.