https://www.law.cornell.edu/uscode/text/18/597
> Whoever makes or offers to make an expenditure to any person, either to vote or withhold his vote, or to vote for or against any candidate; and
> Whoever solicits, accepts, or receives any such expenditure in consideration of his vote or the withholding of his vote—
> Shall be fined under this title or imprisoned not more than one year, or both; and if the violation was willful, shall be fined under this title or imprisoned not more than two years, or both.