One of the most promising recent trends in expanding political participation has been allowing people to vote in the weeks before Election Day, either in person or by mail. Early voting, which enables people to skip long lines and vote at more convenient times, has been increasingly popular over the last 15 years. It skyrocketed to a third of the vote in 2008, rising particularly in the South and among black voters supporting Barack Obama.

And that, of course, is why Republican lawmakers in the South are trying desperately to cut it back. Two states in the region have already reduced early-voting periods, and lawmakers in others are considering doing so. It is the latest element of a well-coordinated effort by Republican state legislators across the country to disenfranchise voters who tend to support Democrats, particularly minorities and young people.

The biggest part of that effort, imposing cumbersome requirements that voters have a government ID, has been painted as a response to voter fraud, an essentially nonexistent problem. But Republican lawmakers also have taken a good look at voting patterns, realized that early voting might have played a role in Mr. Obama’s 2008 victory, and now want to reduce that possibility in 2012.

Mr. Obama won North Carolina, for example, by less than 15,000 votes. That state has had early voting since 2000, and in 2008, more ballots were cast before Election Day than on it. Mr. Obama won those early votes by a comfortable margin. So it is no coincidence that the North Carolina House passed a measure — along party lines — that would cut the early voting period by a week, reducing it to a week and a half before the election. The Senate is preparing a similar bill, which we hope Gov. Beverly Perdue, a Democrat, will veto if it reaches her.