Bob in The Atlantic:

Only months before November’s elections, the Republican National Committee has launched a new legal attack on the rules that govern federal elections. Supported by 24 states, the RNC is seeking, on an emergency basis, a Supreme Court ruling that the United States Congress lacks the constitutional authority to regulate presidential elections—congressional elections, yes, but not elections held to select presidents. The petitioners’ immediate goal is to allow the state of Arizona to impose a “proof of citizenship” requirement as a condition of a person’s right to vote for president.

If they are to succeed, the Court will have to suddenly, with mere weeks left before people start voting, abandon or explain away a decision it rendered in 2013—that Congress has the power to establish rules for voter registration in presidential elections. But even if the suit fails, it risks achieving some success in sowing doubt about the integrity of elections, highlighting claims of illegal voting by immigrants, and laying a foundation for post-election allegations of fraud and related legal challenges. (I have advised the national Democratic Party on this suit and have been further monitoring it as part of nonpartisan work to support election administrators in their preparation for the fall elections.)…

The earlier 2013 decision is one hurdle that the RNC and its allies confront, but not the only one. The Court has made clear in other cases, as in those involving presidential campaign finance, that Congress does indeed have the power to regulate presidential elections: “Congress has the power to regulate Presidential elections and primaries,” the Court said in Buckley v. Valeo, affirming its position in the earlier case of Burroughs v. United States, that Congress can use that power to safeguard those elections from corruption.

The Court has also upheld Congress’s authority to lower the voting age in presidential elections, to prohibit disqualification of voters in presidential and vice-presidential elections for failure to meet state residency requirements, and to provide uniform national rules in those elections for absentee voting. Additional federal laws on the books for years protect against the coercion of voters in presidential elections and ensure that members of the armed forces and other overseas voters have access to the ballot.