The guy would have standing to sue as a member of the Democrat Party and as a Voting Citizen of the United States. “
IMO, Every properly registered voter in the USA has “standing” to prevent someone who is not qualified under the terms of the Constirution to run for office.
If we all don’t stand up for the Constitution, we will fall for anything.
The Constitution also requires a case and controversy. Seems like this is a political question, not a judicial one.