Lobbyist Jack Abramoff and former California Rep. Randy “Duke” Cunningham are among the many Republicans whose ethical misconduct have prompted Democratic strategists to conclude that the Republican-run Congress has fostered a “culture of corruption.” But in the run-up to an April 11 special election in California’s 50th District, which Cunningham vacated after pleading guilty to federal corruption charges, it is a Democrat — Francine Busby, an educator and school board trustee — who has had to defend herself against Republican attempts to link her to lobbyists. The National Republican Congressional Committee (NRCC) this week unleashed a television attack on Busby,...