In America, Hillary Clinton holds a solid and enduring 15- to 20-point lead over Barack Obama, who, in turn, enjoys a 2-to-1 advantage over John Edwards, who languishes in third place. But in Iowa, Edwards is often in first place in the polls and, at best, Hillary is locked in a three-way tie with her rivals.

In America, Rudy Giuliani continues to lead the Republican field by 10 points while Fred Thompson edges past the ill-fated Mitt Romney and the snakebit John McCain. But in Iowa, it is all Romney all the time as the former Massachusetts governor, riding a wave of paid television ads, has first place all to himself and has been atop the Iowa polls for four or five months. Meanwhile, Arkansas’s former governor, Mike Huckabee, way down in the national polls, is surging in Iowa and now boasts 14 percent in the polls. Ahead of McCain, he is challenging Thompson and Giuliani in the first-in-the-nation caucuses.

So which is reality? Is it the relatively stable national leads of Hillary and Rudy, or the three-way tie on the Democratic side in Iowa and the Romney romp among the state’s Republicans?

The theory is that with the obsessive national focus on the presidential race, which started as soon as the ballots were counted in 2006, the early states no longer are the only ones to get an overdose of the campaign early on. Thus they will conform, some say, to the national trends before long. But Edwards’s enduring strength and Romney’s surge in Iowa may challenge this conventional wisdom.

Edwards’s strong showing in Iowa is largely an historical artifact, the product of his efforts there in 2004 and the assiduous attention he has paid to the state ever since. As such, it’s probable that his strong performance will be overtaken by the national perception that the race is really between Hillary and Obama. As the two national front-runners begin to run ads in Iowa, they should be able to leave Edwards behind. Indeed, there is no reason not to expect Hillary to surge into the lead in Iowa as she already has in New Hampshire and South Carolina.

But on the Republican side, the situation is more problematic. Romney’s surge is entirely Rudy Giuliani’s fault. Ineptly, his campaign chose not to advertise early on in Iowa and ceded the airwaves to Romney. Anxious to display the largest cash on hand, Giuliani made a possibly fatal mistake in letting Romney get a large and sustained lead in the first caucus state.

It remains to be seen whether Rudy and/or Thompson can play catch-up and challenge Romney in Iowa. If Mitt Romney wins in Iowa, he can probably expect to prevail in New Hampshire, where he is also well ahead.

It is one of the media’s blind spots that, while it discounts the performance of a presidential candidate in his home state (Tom Harkin, for example, got no bounce from winning in Iowa in 1992), it does not realize that, in media terms, Massachusetts and New Hampshire might as well be the same state. Most of the Granite State’s residents watch Boston television at night and are used to seeing ex-Gov. Romney in their living rooms on the nightly news, giving him an edge as significant as if it were his home state. In 1992, Massachusetts Sen. Paul Tsongas won the New Hampshire primary and the media accepted it at face value, as they are likely to do if Romney prevails.

If Romney wins Iowa and New Hampshire, will anti-Mormon prejudice and his flip-flop-flip on abortion bring him down, or will he cruise to the nomination?

It is also possible that something else is going on in Iowa. Jaded by the massive amounts of money spent in the state by presidential aspirants, Mike Huckabee seems to be developing a unique appeal as the candidate without money. As he said before the Ames straw poll, where Romney wrote out $35 checks for any of his supporters who wished to pay the obligatory poll tax and vote, “I can’t afford to buy you. I can’t even afford to rent you.” Huckabee’s second-place 18 percent finish at Ames might give an indication of a broader surge behind his candidacy as his electric personality, warm wit and sincere spirituality attract Republicans in droves. (In Texas, California Congressman Duncan Hunter may have shown a similar strength, winning the straw poll with 40 percent of the vote.)