Many people may be voting for Mitt Romney because of the view in some quarters that he is the inevitable Republican candidate for President of the United States and the candidate with the best chance of beating Barack Obama, rather than because they actually prefer Romney to the other candidates.

Inevitability has a very unreliable track record. Within living memory, totalitarianism was considered to be "the wave of the future." During the primary season, people should vote for whomever they prefer, on their own merits, not because pundits have pronounced them inevitable.

Regardless of what the polls or the pundits say about Mitt Romney's chances of winning the Republican nomination, the conditions that made him the front runner in the primaries are the direct opposite of the conditions for the general election.

The biggest single reason why Governor Romney is the front runner is that he has had the overwhelming advantage in money spent and in "boots on the ground" running his campaign in states across the country.

Romney has outspent each of his rivals -- and all of his rivals put together. His campaign organization has been operating for years, and it has put his name on the ballot everywhere, while neither Santorum nor Gingrich had a big enough organization to get on the ballot in an important state like Virginia.

In the general election, President Obama will have all the advantages against Romney that Romney currently has against his Republican rivals. Barack Obama will have boots on the ground everywhere -- not just members of the Democratic Party organization but thousands of labor union members as well.

Incumbency alone guarantees the president plenty of money to finance his campaign, not only from enthusiastic supporters but also from businesses regulated by the government, who know that holders of political power demand tribute. And the mainstream media will give Obama more publicity than Romney can buy.

How does anyone ever defeat a sitting president then? They do it because they have a message that rings and resonates. The last Republican to defeat a sitting president was Ronald Reagan. He was the only Republican to do so in the 20th century.

He didn't do it with polls. At one point during the election campaign, President Jimmy Carter led Ronald Reagan with 58 percent to 40 percent in the polls. So much for the polls that so many are relying on so heavily today.

The question is not which Republican looks better against Barack Obama in the polls today, before the general election campaign begins. The question is which Republican can take the fight to Barack Obama, as Reagan took the fight to Carter, and win the poll that ultimately matters, the vote on election day.

The biggest fighting issue for Republicans is ObamaCare. Can the author of RomneyCare as governor of Massachusetts make that an effective issue by splitting hairs over state versus federal mandates? Can a man who has been defensive about his own wealth fight off the standard class warfare of Barack Obama, who can push all the demagogic buttons against Mitt Romney as one of the one-percenters?

Rick Santorum, and especially Newt Gingrich, are fighters -- and this election is going to be a fight to the finish, with the fate of this country in the balance. Mitt Romney has depended on massive character assassination advertising campaigns to undermine his rivals. That will not work against Barack Obama.

Even a truthful account of the Obama administration's many disastrous failures, at home and abroad, will be automatically countered by the mainstream media, 90 percent of whom voted for Obama in the 2008 election.

It is truer in this election than in most that "it takes a candidate to beat a candidate." And that candidate has to offer both himself and his vision. Massive ad campaigns against rivals is not a vision.

Some, like President Bush 41, disdained "the vision thing" -- and he lost the presidency that he had inherited from Ronald Reagan, lost it to a virtual unknown from Arkansas.

The vision matters, more than the polls and even more than incumbency in the White House.