Democrats sue to ease absentee voting in Pennsylvania and S.C.

Democrats continued their aggressive legal strategy to make voting easier on Wednesday, filing lawsuits seeking to expand mail-in balloting this year in both reliably red South Carolina and premier battleground Pennsylvania.

The suits are the latest in the party's multimillion-dollar campaign against a wide range of laws and regulations it alleges are illegally and unconstitutionally suppressing the vote, particularly in poorer and minority areas.

Republicans are vowing to spend as aggressively defending the provisions under challenge. But the effort has already brought victories for Democrats — on issues ranging from...