Jon Rauch says it well:
We know what happens when movements or parties continue to stagger forward after running out of ideas: They become zombies. Zombie parties are a recurrent feature of electoral democracies. Unable to articulate any coherent or workable governing philosophy, they mindlessly jab at cultural hot buttons, mechanically repeat hardwired tropes ("cut taxes, cut taxes, cut taxes"), nurse tribal resentments, ostracize independent thinkers. Above all, they feel positively proud of their doggedness. You can’t talk them out of it. Think of the Republicans in the FDR years, the Democrats in the Reagan years, the British Labour Party in the Thatcher period, and the British Conservative Party in the Blair period. Think of Japan’s Liberal Democratic Party for most of the past half-century, or France’s Socialists today. To get a new brain, zombie parties usually need to spend years out of power or wait until a new generation rises to leadership.
Lexington wants to add Gordon Brown's Labour Party to the list.