Democratic insurgents hoping to topple House Minority Leader Nancy Pelosi (D-Calif.) lack a key ingredient in their master plan: a formidable challenger.

Pelosi’s detractors have argued for years that Democrats need an image overhaul by empowering newer members at the very top of the party. But they suffered a big setback when Rep. Joseph Crowley (D-N.Y.), thought by many to be Pelosi’s heir apparent, was unseated himself in an astonishing primary defeat earlier this year.