From that same Ryan Lizza article:

Factor has reason to be concerned. In a recent Foreign Affairs article, McCain called for the kind of costly nation-building capacity that makes libertarians shudder, arguing that the United States should “energize and expand our postconflict reconstruction capabilities” and create a “deployable police force” that would prop up collapsing states. Echoing Norquist’s book, Factor insisted that the war in Iraq is not a unifying issue for the right. He told me, “The bottom line is that to the base of the Party the war isn’t Communism—to the Republican Party under Ronald Reagan, Communism was a rallying point. This is not like that.”

This is true.  There was almost unanimous consensus about the Soviet threat and about the appropriate response to it, and there simply isn’t the same degree of agreement on Iraq.  The glue of anticommunism was far stronger and more powerful, for both good and ill, than support for the Iraq war taken in isolation.  The GOP has become by and large a party defined by the war, and McCain’s nomination will confirm that, but it has also been the last five years that have seen the GOP go from an ascendant, would-be majority party to its current miserable state.  That is one reason why, of course, supporters of the Iraq war have made tremendous, completely unpersuasive efforts to link Iraq to a broader anti-jihadist effort, because I think that even they know that an open-ended nation-building project in the Near East will lose the support of many of the American nationalists who make up the ranks of the party.  Even general anti-jihadism doesn’t seem to succeed in unifying Republicans in quite the same way that the Cold War did, probably because enough Republicans and conservatives understand that the threat from jihadis, while real and grave, will never be on the same scale as the Soviet threat and that attempts to claim that they are comparable strain credulity.  The GOP’s problem is that no other single issue unites as many factions around McCain as the war, but even the war is insufficient as a rallying cry to unite the entire party, since at least one third of the party openly opposes the war.