Pre-election there is vetting by voters in the prelims and the general. Each state can have laws controlling ballot access. Candidates may have standing to challenge misapplication of the qualification process.
Post election, we have the electoral college and Congressional certification.
Post inauguration, we have impeachment/removal, re-election, and term limits.
What we don’t have, based on the standing doctrine favored more strongly by the conservatives on the Supreme Court than the libs, is a trial lawyer/activist judge path.
If you do not like it, we have the Constitutional Amendment process, but likely applied prospectively, not retroactively.
And none of that matters one wit if we demonstrate your hero is a fraud.