> “But the Federal elections for House, Senate and President/Vice President could constitutionally be structured with federal laws.....................”
Yes, at least the top of the ticket which is a national election.
1) There are no Presidential elections in the Constitution.
2)Therefore, there is no Federal Constitutional right to "vote for President".
3) The separate processes by which 50 State Legislatures apppoint their Electors for President and Vice President are not Federal elections.