A system of file maintenance that makes a reasonable effort to remove registrants who are ineligible to vote from the official list of eligible voters. Under such system, consistent with the National Voter Registration Act of 1993 (
42 U.S.C. 1973gg et seq.) [now
52 U.S.C. 20501 et seq.], registrants who have not responded to a notice and who have not voted in 2 consecutive general elections for Federal office shall be removed from the official list of eligible voters, except that no registrant may be removed solely by reason of a failure to vote.