Some contend that section 3 of the 14th Amendment, which bars former insurrectionists from public office, bars Donald Trump, and there is major legal debate on the issue.
Attorney Don Kilmer points out that §3 also allows Congress to remove that bar by a 2/3 vote, and in 1872 Congress did so as to all but a handful of offices, not including the presidency. 17 Stat. 142.