SAN FRANCISCO — San Francisco would become an electoral test tube under a proposed ballot measure to establish a second day of voting in next year’s general election, the Saturday before the traditional Tuesday in November.

Alex Tourk, a local political consultant who is organizing the campaign, said his motivation was to prove that “weekday voting creates barriers.” He cited work, child care issues and fatigue as reasons people stay home from the polls.

“It’s all just about increased access,” Mr. Tourk said.

The idea of weekend voting is not unheard of. Louisiana has long had Saturday voting for a variety of elections, but not for November’s biennial general elections, which are still only on the first Tuesday of that month.

Some states have limited voting on the Saturday before a Tuesday election in centralized locations, like county election offices or other governmental offices, said Paul Gronke, director of the Early Voting Information Center at Reed College.