It is not surprising that a crowded field of candidates is courting the same kind of clergy support in a Feb. 26 special primary election to replace Mr. Jackson, who resigned his Second Congressional District seat 15 days after winning re-election in November. Now facing a short campaign sprint, those candidates say the backing of ministers and invitations to stump at multiple church services each weekend remain the sacraments of any good election ground game in the district, which includes parts of Chicago’s South Side and southern suburbs. Like in many districts across the country where African-Americans are the majority,...