Sen. Barack Obama's, D-Ill., chief strategist, David Axelrod, spoke out this morning against accusations that Sen. Hillary Clinton, D-N.Y., was never vetted for the vice presidency.

"I can tell you, the first person that [Obama] sat down and talked to at all about this vice presidential issue was Sen. Clinton. They had a discussion back in early June about it, and he spent more time with Sen. Clinton alone, talking about issues, than he has with Joe Biden or anyone else in the last couple of months. So, that's simply not true," Axelrod explained in an exclusive interview on "This Week With George Stephanopoulos."

The McCain campaign pounced on the issue Sunday morning, releasing an ad attempting to rile up former Hillary supporters. "She won millions of votes. But isn't on his ticket. Why? For speaking the truth?" the ad asks amid clips of Clinton targeting Obama during the primary season.

Axelrod went on to explain why Obama opted for Sen. Joe Biden, D-Del., instead of the former first lady: "[Obama] has a high regard for Sen. Clinton ... She's going to be an important voice in moving this country forward in the next administration. But he felt that Sen. Biden would be the best fit for him at this time."

In a separate interview, former Republican presidential candidate Rudy Giuliani questioned Obama's decision not to pick Clinton. "The strong choice would have been Hillary Clinton. The obvious choice would have been Hillary Clinton," Giuliani said. "She had 50 percent of the Democratic vote. Obama has 50 percent of the Democratic vote. You almost have to go to extraordinary lengths to avoid her as the vice presidential pick of the party."

"Sen. Obama has made a choice more out of weakness than strength," Giuliani continued. "Don't go with your strongest candidate, and then go with a candidate that actually emphasizes all your weaknesses and has been quite vocal about them."

And while the former mayor of New York welcomed Biden "to this whole effort again," he made clear that he has no intention of joining him on the campaign trail as McCain's running mate. "I have not been, as far as I can tell, vetted, if they do tell you about that," he said. "I am certain that the candidate -- it's down to three or four candidates. It is not me."

By Mary Bruce, ABC News, August 24, 2008