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As an outsider, Herman Cain's strategy of campaigning all over the country, promoting his book and avoiding retail politics makes absolute sense. -- That's what has appealed to Republican voters in the last several months as we've seen Cain's popularity soar.

There was an authenticity, a sense of optimism and enthusiasm, indeed an almost an evangelical appeal to Cain's outsider bid for his Party's nomination.

However, now that Cain is the acknowledged front runner for the Republican presidential nomination the world has changed.

In Thursday's Wall Street Journal/NBC News poll 27% of Republican primary voters chose Cain as their first choice to be the Party's nominee. Mitt Romney was the second choice among Republican primary voters with 23% of voters naming him as their choice take back the White House.

Now, the question for Republican primary voters goes from "should we register our protest vote by choosing Herman Cain" to "should Herman Cain be the next president of the United States?"

To help primary voters make that leap Cain has to do several things. First, he has to campaign in primary states -- something he hasn't been doing. That means he is going to have to campaign in Iowa, New Hampshire, South Carolina and Florida.

Next, he's got to prove that he's a real candidate, not just a symbol and that he can deal with the back and forth that's required --every day -- on the campaign trail.

So far, the evidence is not good that Cain can make the transition from protest candidate to genuine, serious presidential candidate.

First, the former businessman does not have much of an operation on the ground in key states.

His 9 - 9 - 9 plan is a good start but he also needs to talk about other issues, including foreign policy to show that he is a real candidate.

Important political strategists have also spoken with Cain to tell him that he needs to change his approach, that his way of doing things won't work in the long term, but they have been rebuffed. For the moment, Cain is still insisting on doing it his way.

None of this means that Cain can't win. He can. In fact, the former Godfather's Pizza CEO is the only candidate to generate real enthusiasm among Republican primary voters.

Contrast this enthusiasm to feelings about Mitt Romney, who has been stuck at 25% for as long as I can remember. In fact,  all the establishment endorsements Romney keeps collecting may just wind up hurting him more than helping him because voters are angry at the establishment.

Bottom line: There's simply no denying that Herman Cain has to perform differently from now on than he did before. The jury is still out on whether can make transition from protest candidate to bona fide presidential candidate and even to the next occupant of the White House. Only time will tell.

Douglas E. Schoen is a political strategist and Fox News contributor. His most recent book is "Mad as Hell: How the Tea Party Movement is Fundamentally Remaking Our Two-Party System" published by Harper, an imprint of HarperCollins.