Would it be legal for the federal government of the United States to introduce a law, with words to the effect of:
"No results of any congressional, senatorial, or presidential election may be announced until polls have closed in all participating states."
Whilst I believe the conduct of the elections is in near complete control of the state, would this extend to announcement of the results?
The rationale behind this law would be to prevent announcing earlier results in an attempt to influence later voters - for instance apparently the first polls will close at 1800 Eastern Time in Indiana and Kentucky, at which time some voters in Alaska will apparently still have 7 additional hours to cast their ballot. A similar provision applies in European Parliamentary elections, where votes are not permitted to be counted until Sunday, when the final polls close.