Virginia Senate Majority Leader Thomas K. Norment Jr. (R-James City). (Steve Helber/Associated Press)

THE INTENT of Virginia’s ban on voting by convicted felons was to weaken the political power of black people, whose electoral clout was abhorrent to the racists who enacted the prohibition a century ago. Today, Virginia Republicans, who have done their utmost to dilute minority voting by enacting arbitrary voter-ID requirements, are animated by the same idea.

Determined to block any surge in African American electoral participation in November, which would mainly benefit Democrats, they are planning litigation to challenge Gov. Terry McAuliffe’s executive order that restores voting rights to more than 200,000 former convicts who have finished serving their felony sentences.

When Richmond’s GOP leaders embarked on their campaign to tighten voter-ID laws, they could cite no widespread or credible problem with fraud at the polls. Today, similarly, they can point to no constitutional language preventing Mr. McAuliffe, a Democrat, from restoring voting rights to ex-convicts — something that takes place routinely in most states.

“Governor McAuliffe’s flagrant disregard for the Constitution of Virginia and the rule of law must not go unchecked,” declared Senate Majority Leader Thomas K. Norment Jr. (R-James City), who cited no provision in law or the constitution to buttress his claim.

No wonder Richmond Republicans are floundering. The leading expert on (and the principal draftsman of) the state constitution, University of Virginia law professor A.E. Dick Howard, has said Mr. McAuliffe has “ample authority” to restore voting rights to felons who have paid their debt to society. And Mr. McAuliffe’s GOP predecessor, former governor Robert F. McDonnell, encountered little resistance from fellow Republicans when, just three years ago, he established a system to automatically restore the vote to thousands of nonviolent former felons annually.

No principle distinguishes Mr. McAuliffe’s move from Mr. McDonnell’s; what’s different is the scale. While Mr. McDonnell’s move empowered perhaps 10,000 ex-convicts, Mr. McAuliffe’s covers 206,000 in one fell swoop, with more to come as they become eligible.

Republicans insist Mr. McAuliffe has overstepped by not restoring voting rights on a case-by-case basis. But the constitution says nothing to require any such individualized review, and Mr. McDonnell himself ignored that nicety.

A surge in voting by former felons, who are disproportionately black, might tilt Virginia, a swing state, toward the Democrats. Mindful of the stakes, the Republicans have hired the biggest legal gun they could find to challenge the governor’s executive order: Charles J. Cooper, an assistant attorney general in the Reagan administration.

The ban on voting by felons has disenfranchised nearly a quarter-million African Americans in Virginia, about a fifth of the total. Mr. McAuliffe’s office has issued extensive citations from the constitution, under which a felon is banned from voting “unless his civil rights have been restored by the Governor” and further empowers the governor to “remove political disabilities consequent upon conviction.”

That looks like sufficient constitutional basis for Mr. McAuliffe’s action, on top of the moral imperative of erasing one of the last and most noxious vestiges of Jim Crow in Virginia.