CHICAGO - US presidential hopeful Mitt Romney easily won the key Illinois primary Tuesday, making him ever closer to the Republican nomination.

But his winning the race is far from being guaranteed unless he could avoid the gaffes that have characterized his campaign.

Romney beat his closest challenger, Rick Santorum, 47 percent to 35 percent in Illinois, a solid win that seemed as if it might finally end questions of Romney's electability and bring a quick close to the Republican nominating contest.

Romney used the opportunity to try to pivot to the general election, telling those at his Illinois victory party that he offered a different vision for the United States than President Barack Obama and calling for general support.

Wednesday morning, political analyses that again acknowledged Romney as the inevitable nominee lined US newspapers, with commentators seeming to agree that his rivals had given it their best shot but the time had come for conservatives to unite around Romney.

Romney then added to his Illinois momentum, picking up a crucial endorsement from former Florida Governor Jeb Bush, brother of former US President George W. Bush and a respected leader within the Republican Party.

But then someone from the Romney campaign went on national television and made a silly mistake that could, against all odds, reignite the Republican nomination contest.

Asked on CNN if the Republican primary process could hurt Romney in a general election by making Romney adopt very conservative viewpoints that energize the Republican base but alienate the general American electorate, Romney's senior campaign adviser Eric Fehrnstrom said Romney could erase the positions he had taken during the primaries and start over in the general election.

"I think you hit a reset button for the fall campaign. Everything changes," Fehrnstrom said.

"It's almost like an Etch A Sketch. You can kind of shake it up, and restart all over again," Fehrnstrom continued, referring to the childhood toy that can be simply shaken to erase the image scrolled onto it.

The comment might seem relatively harmless, given its lack of any negative language or extremism, but it was exactly the sort of statement Romney's challengers were hoping for to offset Romney's otherwise silencing victory Tuesday night.

Candidates Santorum and Newt Gingrich, who only one night before seemed to be running out of steam, now have yet another opportunity to warn people that Romney is not a true conservative, but simply acting a part.

Santorum and Gingrich were consequently both eager to milk the Romney gaffe for maximum publicity at campaign events in Louisiana on Wednesday, both carrying Etch A Sketches onto the stage and using them as props to stir up voters.

"You could not have found a more perfect illustration of why people distrust Romney than to have his (adviser) say that the Etch A Sketch allows you to erase everything in the general election," Gingrich told a crowd at one of his rallies.

"You have to read the guy's quote to realize - if he had set out to highlight for everybody why we distrust Romney, I think he couldn't have done a better job," Gingrich said.

Santorum likewise drew the parallel that Romney could not be trusted to represent the views of true conservatives in a general election and that Romney would do and say anything to get elected.

Taken by itself, the Etch A Sketch blunder by the Romney campaign will not cost Romney the nomination, and indeed the former Massachusetts governor will in all likelihood be the Republican choice for president in the coming November.

Romney's opponents are increasingly running out of both the time and money to mount the kind of challenge necessary to keep Romney from getting the nomination. They are, too, each making their own eyebrow-raising comments that cost them voters. Santorum, for instance, said Monday that he did not "care about the unemployment rate."

However, with memorable comments such as "I'm not concerned about the very poor," "I like to fire people" and now the Etch A Sketch do-over reference, the Romney campaign's gaffes seem to go beyond the realm of being taken out of context, analysts said.

Rather, they may be cementing the image of a do-anything-for-a-vote stereotype people most fear Romney to be, they added.

By making such elementary mistakes, the Romney campaign seems to be doing more than the Santorum and Gingrich camp ever could to keep Romney from crossing the nomination finish line for as long as possible, they said.