David Becker is executive director of the nonprofit Center for Election Innovation & Research and former senior trial attorney in the Justice Department’s voting section.

Voting by mail is a wonderful reform, but an overly aggressive expansion for November and limitation of in-person voting could have plenty of unintended, undesirable outcomes. As concern about the novel coronavirus pandemic has skyrocketed in recent days, there have been increasing calls for a move to mail-in balloting for the November elections that would limit in-person voting, as Oregon and Washington already do. On Monday, Sens. Ron Wyden (D-Ore.) and Amy Klobuchar (D-Minn.) wrote in The Post about the coronavirus threat to the November election and their introduction of a new bill to give every American the option of voting by mail. While there are many good things in this bill, making such a dramatic nationwide change is much easier said than done.

Studies have found that voters who prefer mail voting are disproportionately older and white. When given a choice, black and Hispanic voters, in particular, prefer to vote in person at rates about twice that of whites, even when a mail ballot is sent to them as a voting option. (Ballots can usually be mailed back or deposited, without postage, at designated collection boxes.)

Rushing to an all-mail voting system nationwide, without guaranteeing the reasonable availability of in-person polling sites as an alternative, thus risks inadvertently — but profoundly — changing the makeup of the electorate. Turnout by minorities could be dampened because when some states move to mail-in ballots, they often drastically reduce the number of in-person polling stations. While some reduction in polling sites may be necessary in November, too much reduction could lead to even longer lines, thus making things more difficult for voters.

A switch to all-mail, or mostly mail, voting would also be a massive administrative undertaking. It requires planning, training, procurement of new technology and education of the electorate, particularly if in-person voting is being limited. Printing and secure storage of huge increases in paper ballots, postage, secure drop-box locations and additional ballot scanners all must be considered. And more mail ballots could lead to long delays in reporting results.

Election officials would also need to establish a process to prevent double voting by someone who voted by mail and then showed up to vote in person. Other concerns: Because mail ballots aren’t checked for errors by scanners at polling places — voters unaccustomed to the process are naturally more likely to make mistakes — elections could see a significant increase in uncountable (or uncounted) votes. And because states usually require that the signature on the mail ballot match the voter’s signature on file, ballots could be rejected in record numbers.

Do these challenges mean the idea of expanding the use of mail-in ballots for November should be abandoned? Absolutely not. There’s a lot that can be done to encourage the reform in a way that promotes democratic participation without risking disenfranchisement.

First, eliminate the requirement in more than a dozen states that voters must first produce an excuse for needing a mail-in ballot. Make it easy to request a ballot in the mail. A single statewide website for ballot requests is the most convenient.

Second, election officials should engage in an unprecedented effort to promote the use of mail ballots for any voters who feel more comfortable voting that way.

Third, states should begin immediately identifying polling places that will be large enough to accommodate voters in November without requiring them to stand in close proximity for long periods of time. And states need to recruit more poll workers who are a lower risk for infection.

Finally, the federal government and the states must provide additional funding to support these contingencies. Several hundred million dollars might be needed to ensure a smooth process in an election with staggeringly more mail ballots than the nation has ever seen.

The coronavirus pandemic is a real threat to U.S. elections. But if chaos is going to be minimized, a coherent, well-executed plan to expand Americans’ voting options, without limiting the ability to vote in person, is essential. Eight months is barely enough time to make sure it works.

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