Because, with the right-wing press (i.e. 70% or more) on his side, and taking constant pop-shots at Milliband, he can't afford to go one on one in a proper debate, in case people realise that in fact, of the two, Milliband is far more intelligent and honest.
I just cannot fathom why he has spent his life getting to where he is and then, in my opinion, bottling it. The next government need a decisive victory but with this sort of dilly dallying it won't happen.
"He probably thinks he has better things to do running the country"
This is what frightens me about democracy. Do you honestly believe that a Prime Minister runs a country?