While state legislatures have plenary power over the choosing of presidential electors and a great deal of authority over the election of representatives and senators, Art. 1, § 4, cl.1 of the Constitution gives Congress the authority “by Law make or alter such Regulations, except as to the Places of chusing Senators.”
I propose that Congress intact legislation requiring that the election of Representatives and Senators be solely by paper ballots that are hand counted in the presence of representatives of all candidates who wish to have an observer present, and that any challenged ballots be set aside for adjudication at a public hearing. All ballots would be subject to verification that they actually were cast by a lawfully-registered, living voter who had cast only one ballot. In order to prevent disenfranchising any disabled voters, Congress should mandate the use of assistive technology using audited open source hardware and software approved by a comment agency (such as the National Institute of Standards and Technology) that is always available for public inspection. The paper ballots thus generated would then be counted like any other.
Congress can’t force states to use any method for choosing presidential electors, but it could entice states to use the proposed system by offering to pay for the assistive technology required if the states choose to using the same system for presidential voting.