Of course Rather is stonewalling. Admitting fraud, he'd have to offer up his source, one way or the other. And that would lead right back to his masters at the DNC and the Kerry campaign. Which would effectively end Kerry's chances. The fact that it would end Rather's career is immaterial -- he'd resign in a flash over this if he could keep the Democrats out of it. But he can't.
So, like Nixon, they'll lie, attack, distract, bribe and threaten until they can get past the election with a fighting chance.
I wonder if Rather understands Nixon better now. I'm sure he will, in time.