I agree that it's a normal example of Trump running his mouth like when he said he would invade Greenland.
He has no right to federalize elections, but Congress can set standardized rules.
Hat tip to
@Orange_Crush.
https://constitution.congress.gov/browse/essay/artI-S4-C1-3/ALDE_00013640/
The [Elections] Clause is a default provision; it invests the States with responsibility for the mechanics of congressional elections but only so far as Congress declines to pre-empt state legislative choices. Thus, it is well settled that the Elections Clause grants Congress ‘the power to override state regulations’ by establishing uniform rules for federal elections, binding on the States. ‘The regulations made by Congress are paramount to those made by the State legislature; and if they conflict therewith, the latter so far as the conflict extends, ceases to be operative.'
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