The state has a primary role when it comes to making decision on who gets to vote.
According to Lyle Denniston, adviser on constitutional literacy of national constitution center “The constitutional rights, powers, and privileges of establishing voter qualifications, including voter registration requirements, are incidents of state sovereignty protected by Article I, Section 2 of the Constitution, the Tenth Amendment, and the Seventeenth Amendment. This power includes the power to obtain information the states deem necessary to assess eligibility or voter registration applicants, and to enforce voter qualifications. A mere oath without concrete evidence of citizenship does not suffice.”