Clarify and extend meaning of "republican form of government" in Article Four:
Affirmative right to vote and access to voting systems for all adult citizens.
Secure, transparent, secret ballot voting systems with independent statistical tests for accuracy.
Automatic, non-partisan electoral districting with the algorithm spelled out. (E.g.: Districts must be equal in population to within 0.5% and maximally compact (for some given definition of compact.))
Eliminate Electoral College; all adult US citizens directly vote for President and Vice President, regardless of where they live.
Uniform rules for election of elected federal officials (President, VP, Senators, Representatives):
Nonpartisan ranked-voting primaries for elected federal offices, to happen a fixed amount of time before the general election. Primary elections eliminate all but two candidates for office using instant-runoff rules.
Uniform rules for getting onto the primary ballot via a standardized petition process. Limit on number of primary candidates, with priority given to those with the most petition signatures.
Clarify that non-person legal entities are not people. The rights protected by the Constitution are the rights of natural persons only.
Federal elected officials must use a true blind trust.