Arthur Branch is the kind of prosecutor that Republicans dream about. The blunt-spoken New York district attorney supports the death penalty, opposes abortion and espouses a conservative legal philosophy that infuriates liberal colleagues.

Unfortunately for Republicans, Mr Branch is a fictional character in Law & Order, the popular US television drama. But Fred Thompson, the actor who plays the role, is a real-life conservative whom many Republicans are counting on to breathe fresh life into the party’s 2008 presidential race.