Can Republicans Embrace Voting by Mail? Pennsylvania Offers a Test.

When voters turned out in February to fill a vacant seat in the Pennsylvania House of Representatives, the stakes were nothing less than control of the chamber, which Democrats held by a single seat.

Candace Cabanas, the 45-year-old Republican candidate who was running as a working-class mom, faced an uphill battle, though not a hopeless one in a competitive district that has long favored Democrats.

But as Election Day dawned, a nor’easter dumped several inches of snow, stranding would-be voters at home. Bad luck dogged others: One woman backing Ms. Cabanas skipped the polls after she fell ill and was rushed to the hospital.

Ms. Cabanas’s Democratic opponent faced similar hurdles but had one advantage: More than 3,300 of his voters had mailed in their ballots early. Ms. Cabanas could count only 532.

Guess who won?

February’s lesson is not lost on Republican leaders in Pennsylvania, who have pledged to spend millions of dollars this year to promote voting by mail despite claiming for years — without evidence — that mailed votes are riddled with fraud. The national party is also pressing a pro-mail publicity campaign called “Bank Your Vote,” apparently after concluding that staking its candidates’ fates on a hefty Election Day turnout was not an optimal strategy.

They may have their work cut out for them. “Persuading Republican voters to use them is really difficult. They don’t trust the system,” Ms. Cabanas said of mail ballots.