The oldest candidate in the race for president should be the last to prey on older voters with deceptive mailings. Yet John McCain's name is on a mailing sent to older Democrats in at least five Florida counties that claims they are registered as Republicans — and asks for campaign contributions. This mailing, paid for by the Republican National Committee, makes use of some of the sleaziest campaign tactics. It apparently uses incorrect or fraudulent voter identification numbers, and it arrives on official-looking forms titled "voter registration tracking forms.'' One of its devious aims appears to be to build lists to challenge the eligibility of legitimate voters. Such an effort to confuse older voters is contemptible, and McCain should denounce it.