Weaver and Nelson have critics, too. One complaint is that they built McCain’s team too fast and too big.
Said University of Virginia political scientist Larry Sabato: "I can see what they were doing and why. The aura of inevitability is a tough thing to beat -- look at Hillary. The problem is that while Hillary is beloved by 88 percent of Democrats, McCain was never a favorite of a big chunk of Republicans."
Weaver said McCain’s anointing as the GOP frontrunner -- which was "nothing that we sought nor a place we wanted" -- was damaging.
"It was something that was thrust upon the senator a year and a half ago -- and once that happens, you have to conduct yourself in that manner because you can lose that pretty quickly, as we saw.
"Politics is driven by policy," he said. "And the senator, to his lasting credit, chose policy decisions that he believes in ... and in doing so, that has ramifications."
Weaver said critics who claim McCain lost his "Straight-Talk Express" appeal are wrong, because "people like straight talk when they agree with it. People tend to not like frank and straight talk when they disagree with it."
To him, that reflects a key difference between McCain in 2000 and in 2007.
"McCain has been as independent as he has ever been," he says. "When you look at torture, climate change, Iraq and immigration ... three of the four don’t necessarily really set well with Republican primary voters."
Weaver said McCain is still the same person speaking his mind, but the political dynamics are different.
The solution, he said, "is to make it more about the character of the man vs. the specific policy position."