You've stated what many FReepers don't understand!
We need a single election voter law that applies equally to all States. That law needs to ensure that legal voters are verified; that all ballots are paper, submitted at the precinct and that all votes are auditable from submission to election certification and beyond.
This suggestion flies in the face of states-rights but IMHO, when a state's incompetence or fraud puts people in power who can affect not just their state but the nation - we need a federal law that will mitigate a state's fraud and incompetence.
With that move you collapse federalism.
Federalism and the Constitution
Another basic concept embodied in the Constitution is federalism, which refers to the division and sharing of power between the national and state governments.
(the footnotes at the site (hover over them or pick it) are informational)
(everyone knows how enlightening footnotes can be)
JMO, YMMV