Robert F. Kennedy Jr. was expected to appear in court Tuesday to defend his effort to get on the ballot for president in the premier battleground state of Pennsylvania, where Democrats are angling to force him off in what is expected to be a closely contested race.

Democratic Party-aligned challengers say Kennedy's candidacy paperwork states a false home address—an allegation being aired in other state courts—and contains other damning shortcomings, such as the wrong names of people who supposedly attested that they gathered the signatures of thousands of voters.