Amendment XXVIII, (proposed), Section 2: "[…] and impartially conducted elections,”
Political parties, which are private organizations, barely existed here in 1787 and are not addressed in the Constitution at all. They benefit government functioning in many ways and it's hard to imagine American politics functioning without them (although some are willing to try) but partisanship has distorted American politics to the point where their involvement in some public functions has to be restricted. Section 2 doesn't prevent parties from running candidates or taking part in the political process but they won’t control certain public functions. This section also forbids using partisanship in influencing any electoral function such as granting (see The Impartiality Clause, Frozen Apportionment, and Partisanship in Public Electoral Functions).
Parties will use the same campaign grants as other groups or individuals.
Amendment XXVIII (proposed), Section 1:
“The people of the United States
will ordain and establish United States government under this Constitution, […]”
Section 1's opening clause ensures that the people will ordain and establish government.
By requiring democratic elections, it ends such distortions of democratic electoral process as ‘superdelegates’, created by the Democratic party, that don’t derive from voting tallies.
But doesn’t the Preamble already say that?
"We the People of the United States,
in Order to form a more perfect Union, establish Justice, […]
do ordain and establish this Constitution for the United States of America."
The Preamble asserts that the people have the right and power to ordain and establish government, and that we agreed to ordain and establish the Constitution as our instrument
governing the United States.
But we’ve failed to uphold it (see The Most Important Clause in American Law).
And even after restoring the Preamble, Section 1’s wording will be useful.
It makes it clear that the people will continue to ordain and establish government ourselves,
not just through the Constitution. This expresses a nuance that we’ve always taken for granted.
If our current situation has taught us anything, it’s that we can’t afford to leave the fundamental power of a democratic electoral process as an implied power.
By steadily reclaiming our political rights and powers,
we invest in our collective future.