This story has been updated.

The general election may turn out to be the Etch A Sketch phase of the presidential campaign, but the GOP primary remains in Rock ’Em Sock ’Em Robots mode.

Former Pennsylvania senator Rick Santorum is coming out swinging against Mitt Romney for a remark Wednesday morning in which a top adviser to the former Massachusetts governor likened the general election campaign to an Etch A Sketch, the toy that can be used to draw a picture with aluminum powder and then wiped clean with a shake of the hand.

Romney’s camp has defended adviser Eric Fehrnstrom for the remarks, arguing that he was referring to the dynamics of the campaign and not to Romney’s issue positions.

But that hasn’t stopped the Santorum camp from seizing on Fehrnstrom’s comment, marking the latest instance in which Santorum has echoed Democrats in his criticism of his GOP primary rival.

@RickSantorum studying up on @MittRomney policy positions yfrog.com/odl78wmj

— Matt Beynon (@mattbeynon) March 21, 2012

“One of Governor Romney’s aides today on television said that Governor Romney, after he wins the primaries, will be like an Etch A Sketch — you take whatever he said and you can shake it up and it will be gone, and he’s going to draw a whole new picture for the general election,” Santorum said Wednesday morning at a campaign event in Harvey, La.

“Well, that should be comforting to all of you who are voting in this primary — that whoever you are going to vote for is going to be a completely new candidate, remove all trace of any kind of marks and be able to draw a new picture,” he continued.

The general-election picture Romney might draw, Santorum argued, might be one “sort of like when he ran for governor of Massachusetts, not as a conservative.”

“One thing you can say — even my staunchest critics will say — is what you see is what you get,” he said.

Santorum’s spokesman, Hogan Gidley, also hammered Romney for the remark in an appearance on MSNBC Wednesday afternoon.

“The bottom line is he wants this race to be over so he can start to tack back to who he is at his core, and that’s a moderate,” Gidley said.

And, on Wednesday afternoon, CBS/National Journal reporter Rebecca Kaplan tweeted that Santorum spokeswoman Alice Stewart was handing out mini Etch A Sketch boards in a parking lot outside a venue in Arbutus, Md., where Romney was speaking.

Former House speaker Newt Gingrich (R-Ga.) joined Santorum in criticizing Romney on Wednesday afternoon.

“Etch a Sketch is a great toy but a losing strategy,” Gingrich said via Twitter. “We need a nominee w/ bold conservative solutions.”

Etch a Sketch is a great toy but a losing strategy. We need a nominee w/ bold conservative solutions. Newt.org #RomneyToys

— Newt Gingrich (@newtgingrich) March 21, 2012

At a campaign event Wednesday afternoon in Lake Charles, La., Gingrich held up an Etch A Sketch and peppered his speech with references to the toy, reports Politico’s Ginger Gibson.

“Newt gave the etch-a-sketch to a kid in the front row and said, ‘You can now be a presidential candidate,’ ” Gibson reported via Twitter.

Santorum’s campaign has pursued a “kitchen sink” strategy against Romney in recent days, and the Etch A Sketch criticism would appear to be the latest in that line of attack.

But whether it’s a fruitful strategy remains an open question. In Illinois, which held its primary on Tuesday, Santorum placed a distant second, trailing Romney by nearly 12 percentage points.

Henderson reported from Louisiana.

This post has been updated since it was first published.