In North Carolina, Republicans are resisting proposals to ease requirements for witnessing absentee ballots during the pandemic. In Georgia, GOP officials have set up a new task force to scrutinize absentee ballots, a move that critics say amounts to voter intimidation.

In Michigan, Republicans are defending the constitutionality of laws that sharply restrict the collection of absentee ballots by third parties — a practice critics call “ballot harvesting,” which Republicans have blamed for their widespread losses in California in the 2018 midterm election.

There is a risk to expanding mail voting, according to election experts, but it is not fraud. The tracking safeguards that are layered over mail-voting systems already offered to many millions of Americans — particularly the requirement for matching the signature on the ballot envelope to a signature on file — make misuse of ballots easy to detect.

The bigger challenge, experts say, is that those safeguards can mistakenly block valid voters because, for example, a signature varies slightly from the one on file or their mailing address in government records is out of date.