Republicans are reeling after the Democrats’ special-election victory last week in Kentucky, but they are gearing up for another big fight, in South Dakota. With three months to go until the June 1 special election, Republican state Sen. Larry Diedrich, the GOP’s candidate to replace Bill Janklow (R), has been making fundraising visits to House Republicans and the House Republican Conference office. His opponent is Democratic attorney Stephanie Herseth, and the National Republican Congressional Committee (NRCC) has begun asking House members to help Diedrich add to his war chest. NRCC spokesman Carl Forti said fundraising efforts will likely parallel those...