A couple options:

1) Interpret it as old-person whinging:

"We are proud of the way our campaign has brought millions of new Americans into the political process. Millions of voters have heard and supported our call to fix what's wrong with the old style of Washington politics. We will continue to call for a change in Washington, whether John McCain likes it or not."

2) Pivot to populism:
"We are proud of the way that millions of ordinary working class and middle class Americans have come out to show their desire to take their country back. We will continue to push for their right to speak louder than the special interests that have dictated Washington business for too long. We know the lobbyists and special interests are afraid of this enthusiasm. It is not surprising that John McCain, whose campaign is riddled with lobbyist influence, is also afraid of the enthusiasm of the everyday American voter."

3) Humor:
"John McCain shouldn't feel so bad. Based on his recent appearances on SNL, as well as his empty rhetoric against the exact same Big Oil donors who are currently funding his campaign, McCain has proven he is the best dramatic actor on the political scene. We're surprised he never considered an alternate career in Hollywood."


As usual, not totally polished but perhaps something along these lines...