John McCain, having clinched the GOP Nomination, is now getting some help from several very successful GOP consultants from past campaigns. Those names include Karl Rove and Ken Mehlman, both of whom are said to be "informally advising the campaign," according to Politico:

Ken Mehlman, who ran Bush’s 2004 campaign, is now serving as an unpaid, outside adviser to the Arizona Republican. Karl Rove, the president’s top political hand since his Texas days, recently gave money to McCain and soon after had a private conversation with the senator. A top McCain adviser said both Mehlman and Rove are now informally advising the campaign. Rove refused to detail his conversation with McCain.

The list could grow longer. Dan Bartlett, formerly a top aide in the Bush White House, and Sara Taylor, the erstwhile Bush political adviser, said they are eager to provide any assistance and advice possible to McCain.

Rove explained that he and McCain “got to know each other during the 2004 campaign.” In a separate interview, Mehlman noted that “McCain was completely loyal to the president in 2004 and worked incredibly hard to help him get elected.” According to Taylor, “The Bush Republicans here in town are excited for John McCain.”

UPDATE:
Karl Rove was on The O'Reilly Factor last night and most of the conversation from the video below is in reference to McCain. The good stuff starts at about 6:10 remaining in the video.