Charles Stewart III, a professor of political science at the Massachusetts Institute of Technology, expressed optimism that states could gear up to expand mail and absentee voting for the coming primary elections, which tend to have relatively low turnout.

The November general election will be another matter, he said.

“I think that once people take a deep breath and consider what’s going to be done in November, they’re going to realize that the big lift necessary to expand the amount of mail voting by a factor of four, five or six in some states is going to be disruptive,” said Mr. Stewart, who studies both voting technology and election administration.

Under normal circumstances, states gradually transition to mail voting.

Mr. Stewart said he worried that states’ lack of experience holding big elections without in-person voting could have negative consequences.

“You can go step by step through the process and realize that there are a lot of details that can cause the mail ballot pipeline to spring leaks,” he said. “The one that’s gotten the most attention in recent years has been the issue of verifying signatures.”

In Maryland, the state’s plan to run its special congressional race by mail — the first time the state has done so for a congressional election — will serve as a practice run in case the state is forced to move to statewide mail-in voting, said former Representative Kweisi Mfume, the Democratic candidate in that race.

“The one good thing that comes out of this is that, for the first time, without having to conduct a statewide mail-in election, the state will have a real opportunity, in a congressional district, to put in place a procedure that is jointly agreed upon and to see to what extent it works,” said Mr. Mfume, who added that he supported the decision this week by Gov. Larry Hogan, a Republican, to move to an all-mail congressional election.

Gaining access to the ballot box has increasingly become a partisan issue, with some Republicans, citing reports of voter fraud, adding hurdles that include purging voter rolls and instituting voter ID requirements, while Democrats promote ideas like same-day registration and early and mail voting options.