A top adviser says the GOP front-runner won't have to stick to conservative positions he adopted during the nomination race.

Updated 4:35 p.m.

Mitt Romney is often chided for his verbal miscues, but Wednesday morning, it was Romney senior adviser Eric Fehrnstrom who put his foot squarely in his own mouth. On CNN, comedian John Fugelsang (of all people) asked whether Fehnstrom was concerned that the primary campaign had forced Romney to move to the right in ways that might hurt him in the general election. Here's Fehnstrom's unintentionally revealing answer:

Well, I think you hit a reset button for the fall campaign. Everything changes. It's almost like an Etch A Sketch. You can kind of shake it up and restart all over again.

As is so often the case with gaffes, the problem is that Fehrnstrom confirms everything that Romney's skeptics believe: that he's a political opportunist, a squishy moderate, and willing to say anything to get elected. This isn't even a flip-flop -- Fehnstrom says plainly that Romney doesn't have to stick to his primary positions. The statement also fits with the complaints of many Tea Party voters about the GOP establishment. They complain that Republican candidates have run on platforms of fiscal responsibility and true conservatism, only to abandon those principles once in office.

It's an open secret that every nominee from the two major parties moves to the center every election year. Fehrnstrom's mistake is speaking that open secret aloud. Republicans may not be surprised, but what voter likes to hear her candidate's adviser state so clearly that she's being duped?

Fehrnstrom, who was last spotted speaking elegantly about the lack of a "deus ex machina" Tuesday night, occasionally gets too clever by half. In August 2011, he accidentally revealed himself as the man behind a fake Twitter account mocking Alan Khazei, a rival of Sen. Scott Brown, another of Fehrnstrom's clients.

As for Romney, he can at least be thankful that the comment comes at the same time that his nomination is starting to look inevitable. Because what started off as your run-of-the-mill campaign gaffe (something of a regularity for Romney on days after big wins) has mushroomed over the course of the day into a potentially defining moment for the Republican campaign.

It's shaping up to be a moment on a par with John Kerry's windsurfing, which the George W. Bush campaign used in a devastating ad suggesting he'd twist and turn "whichever way the wind blows" -- a made-for-TV soundbite with potent metaphorical imagery that reinforces existing negative ideas about the candidate. The Romney campaign says Fehrnstrom's quote is being misconstrued: they say his point -- which is valid -- was that the general election is a beast of its own, in which Republican primary voters will rally around the nominee, and the vast majority of voters who haven't been paying close attention will tune in. Romney's task at that point will be defining itself against Obama, not Santorum or Gingrich or Paul.

You can watch the clip and decide for yourself what Fehrnstrom meant. Either way, Romney's enemies are leaping to take advantage of it. Rick Santorum brandished an Etch A Sketch on stage at his campaign events today, and earlier his team sent out a photo of the former Pennsylvania senator grinning and playing with one:

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Gingrich is doing much the same:

He also had this to say on Twitter in the morning:

Coming the day after nasty losses for both men, they're clearly happy to pile on and mock Romney. Democrats also moved quickly and put out this ad highlighting some of Romney's changes on issues. Apparently there's a cinematographic Etch A Sketch effect, just like the Ken Burns effect:

Democratic operative and frequent Internet trickster Matt Ortega created a similarly themed single-serving website called etchasketchmittromney.com. And that doesn't even count all the digital bric-a-brac floating around the web -- Etch A Sketch portraits of Seamus, etc.

This is all good for a laugh, but it has real repercussions. Today should have been a triumphal day for Romney: he won a decisive victory last night, and this morning he received the much-coveted and long-awaited endorsement of Jeb Bush, a powerful and respected figure in the party whose announcement suggests the establishment is ready to coalesce behind Romney and end the nomination battle. Instead of talking about those two things, though, we're all giggling about toys. And it creates a strategic headache for Romney going forward. Any time he does anything that even vaguely resembles a move to the right, you can expect Democrats to pull out their Etch A Sketches.

The overlooked, substantive story in Fehrnstrom's comment is that he implicitly admitted Fugelsang's premise, that Romney had been pulled to the right by Santorum and Gingrich and that it could make him vulnerable in the general election. Now it will be harder than ever for him to tack back to the center.