An all-mail special election to fill the Baltimore-based seat of the late congressman Elijah E. Cummings (D-Md.) on April 28 will present an early test of how easy it will be to provide voters safer ways to cast ballots during the coronavirus pandemic without discouraging participation.

Maryland Gov. Larry Hogan (R) on Tuesday ordered the election to be conducted entirely by mail. Normally, mail-in balloting is an option for any voter who requests a mailed ballot. But in the state’s 7th Congressional District, a black-majority district that encompasses half of the city of Baltimore and smaller swaths of Baltimore and Howard counties, past participation in mailed ballots has been dismally low, raising concerns among voting advocates about how the state will get the word out to voters.

In last year’s Democratic and Republican primaries for governor, for instance, just under 3,000 voters mailed in their ballots in the 7th District, compared with roughly 72,000 who voted in-person on Election Day and another 33,000 who voted early and in-person.

David Becker, the head of the nonprofit Center for Election Innovation & Research, said moving quickly to an all-mail system raises the risk that there won’t be enough time to educate voters who are unaccustomed to it. And that could harm communities of color disproportionately, he said. A study conducted in five California counties in 2018 showed that black and Hispanic voters were twice as likely to vote in person than white voters, he said.

It will also be challenging for the state to produce the far greater volume of mail-in ballots on such short notice, said Judd Choate, the elections director in Colorado, which spent years implementing its all-mail voting system.

Officials with the Maryland Board of Elections did not immediately respond to inquiries about the special election. Armstead B.C. Jones Sr., the elections director for the city of Baltimore, said he is worried about lower turnout, the difficulty for homebound or ill residents to vote by mail, and the high frequency of younger voters failing to update their voter registration after they’ve moved.

But Jones said he pushed for an all-mail election “because I did not want to jeopardize the staff, the election judges as well as the citizens coming to polling places. I would not intentionally do anything that would hinder anyone from voting.”

The two candidates running in Maryland’s 7th Congressional District, which became vacant after Cummings’s death, are Kweisi Mfume (D), the former president of the NAACP, and Republican Kim Klacik.