VIRGINIA GOV. ROBERT F. McDONNELL (R) has moved to gut an obnoxious bill, championed by Republican lawmakers, that would have needlessly stiffened voting requirements for Virginians. The governor’s level-headed move has annoyed his fellow Republicans, but it has also reaffirmed his reputation as a conservative who has governed mainly as a pragmatist — a reputation that propels him to the short list of Mitt Romney’s putative running mates.

Although he didn’t veto the bill, Mr. McDonnell offered a series of amendments whose effect will be to render the legislation all but moot. That’s a good thing, because the voter ID bill is a gratuitously divisive measure whose only effect would have been to invalidate ballots cast by thousands of poor, young, elderly and minority voters.

Under a state law that has worked well for decades, Virginia voters who lack identification may cast ballots anyway, providing they sign an affidavit attesting to their identity. Falsifying the affidavit is a felony under state law.

The law has never posed a problem; there is no evidence or history of any pattern, prevalence or systematic attempt at voter fraud in Virginia. Nonetheless, Republicans insisted that the law be changed. Under their bill, voters lacking ID could cast only provisional ballots, which would not count unless they faxed an ID to voting officials within a day or presented it personally.

Studies have shown that voters who lack identification tend to be disproportionately elderly, young, poor and black. That means the legislation was blatantly anti-democratic as well as anti-Democratic.

Mr. McDonnell’s proposed amendments would scrap the requirement that voters make a separate trek to local election offices to prove their identity. Instead, election officials would automatically compare signatures on provisional ballots with those on file. If the signatures match, the ballots would count. Voters who still wanted to make sure by presenting proof of identity would have two additional days to do so.

In the 2008 presidential election, about 12,000 Virginians lacked IDs when they cast their ballots. That was a tiny fraction of overall turnout — just a quarter to a third of 1 percent of the 3.7 million Virginia voters that day, according to state elections officials. But in a close election — and plenty of Virginia elections have been very close — those voters could easily provide a margin of victory.

Mr. McDonnell knows something about close elections. When he ran for Virginia attorney general in 2005, his margin of victory was so wafer-thin — 323 votes out of almost 2 million cast — that it redefined “wafer.” In that race, the 6,000 or 7,000 voters who lacked identification could have provided the margin of victory.

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The Post’s View: Suppressing the vote