There was no doubt John McCain would back Mitt Romney for the nomination. The question is, why did the campaign decide to roll this out today, of all days? It’s understandable that Romney would want a big endorsement to help sustain the buzz over his Iowa victory. But the narrative coming out of Iowa is that Romney still has a lukewarm relationship with the base, and he’s only playing into that by appearing with the bane of the conservative grassroots.

There are still conservatives out there who hold a grudge against McCain for losing in 2008, and – rationally or not – cling to the idea that if Republicans had only nominated a more conservative candidate, Obama would never have won the election. McCain’s endorsement is helpful for Romney in New Hampshire, but maybe he should have waited a day or two for the post-Iowa chatter to die down before making the announcement.

Rick Santorum has already used the opportunity to take a swipe at Romney’s moderate record:

“Yeah, that’s fine,” Santorum said when asked about McCain’s planned endorsement. “You know, I would’ve expected that. …

He added: “John is a more moderate member of the Republican team, and I think he fits in more with Newt’s — excuse me, with Mitt’s — view of the world. And I wish him the very best, and again, I have nothing but respect for John McCain.”

Gingrich also pushed the narrative that Romney won’t be able to seal the deal with the GOP base. “The fact is, Gov. Romney has a very limited appeal in a conservative party,” Gingrich said, describing Romney as “a moderate Massachusetts Republican to the left of the vast majority of Republicans.”