Although the qualifications of electors of Members of Congress are
defined by State law,[116] the right to vote for such Representatives is
derived from the Federal Constitution.[117] Unlike the rights guaranteed
by the Fourteenth and Fifteenth Amendments, this privilege is secured
against the actions of individuals as well as of the States.[118] It
embraces the right to cast a ballot and to have it counted
honestly.[119] Where a primary election is made by law an integral part
of the procedure of choice or where the choice of a representative is in
fact controlled by the primary, the Constitution safeguards the rights
of qualified electors to participate therein.[120] Congress may protect
this right by appropriate legislation.[121] In prosecutions instituted
under section 19 of the Criminal Code,[122] the Court had held that
failure to count ballots lawfully cast,[123] or dilution of their value
by stuffing the ballot box with fraudulent ballots[124] constitutes a
denial of the constitutional right to elect Representatives in Congress.
But the bribery of voters, although within reach of Congressional power
under other clauses of the Constitution, is not deemed to be an
interference with the rights guaranteed by this section to other
qualified voters.[125]


WHEN THE ABOVE QUALIFICATIONS MUST BE POSSESSED

The principal disputes which have arisen under these sections have
related to the time as of which members-elect must fulfill the
conditions of eligibility, and whether additional requirements may be
imposed by federal or State law. Although on two occasions when it
refused to seat persons who were ineligible when they sought to take the
oath of office, the Senate indicated that eligibility must exist at the