There is now one question in American politics: With the Republican Party in such bad shape — measured by polls, voter registration, and general enthusiasm — why isn’t Senator Obama in better shape? Most national polls show him slightly ahead.

For some, the answer — or at least part of the answer — is simple: because Mr. Obama doesn’t look like the presidents on American currency. But race in America is anything but simple, and polls seem powerless to measure its political influence.

There is clearly an undercurrent of prejudice in parts of the electorate, evident even among some Democratic primary voters. There is also massive enthusiasm among younger voters to break the color barrier in the Oval Office, coupled with large increases in African-American primary turnout. These unpredictable factors may well balance in Mr. Obama’s favor, which would speak well of the country.

There are explanations enough for a close presidential race without recourse to race.

First, while Senator McCain still lacks a unifying theory for his campaign, his tactics show marked improvement — progress that coincided with campaign personnel changes that included the elevation of Steve Schmidt to head day-to-day operations.

Sometimes the right issue can be even better than the right theory, and for Mr. McCain the energy issue has been a gift. There is perhaps no other topic in American politics today on which the public is angry, seeks action, and agrees strongly with Republicans. Mr. McCain’s approach is to do it all: drilling, nuclear, alternatives, and conservation.

Mr. Obama’s approach has been reactive and irrelevant. What would his redistributed windfall profits tax do to produce energy or reduce the need for it? And Mr. Obama is hamstrung by a coalition that insists we will not drill our way out of this problem — which is true, but beside the point.

No single approach will solve the problem in the short or medium term. And a nation in an energy crisis has every justification to extract its oil and natural gas while it pursues alternatives to oil and natural gas.

Second, Mr. Obama’s tactics are undermining the unifying theory of his campaign. During the primaries, Mr. Obama presented himself as someone different, better, and special. He would not only improve the economy and the health care system, he would transcend old divisions and heal a broken land. Supporters embraced him as inspirational; detractors criticized him as messianic. Few doubt he set the highest rhetorical goals since the New Frontier.

Since the primaries, Mr. Obama has made a tactical decision: He refuses to be painted as a liberal. America may be a discontented country, but it remains a center-right country. Democrats who understand this fact — such as Jimmy Carter and Bill Clinton — become president. Democrats who don’t, lose elections.

But since Mr. Obama’s short public career has been conventionally — in some cases, extremely — liberal, his tactical shift to the center has been startlingly obvious, on issues from guns to terror surveillance to Iraq, and now — reluctantly — to oil drilling.

Says Peter Wehner of the Ethics and Public Policy Center: “Obama’s political calculation may be correct, but it still involves a price. It has shattered his claim to be different. It calls into question his political character, and leaves the impression he is consumed and defined by ambition.”

At least temporarily, Mr. Obama’s tactics have raised a damning political question: Who is this man? And the McCain campaign has begun to cleverly exploit these concerns, not with a frontal attack on his liberalism or his flip-flops, but with a humorous attack on his “celebrity” — really a proxy for shallowness.

The argument is powerful: Mr. McCain has roots and convictions. Mr. Obama has fans and paparazzi. And Mr. Obama’s European trip — more Princess Diana than John Kennedy — served only to confirm these impressions.

All this sets up a fascinating convention season. Will Mr. McCain be able to describe some compelling vision — some combination of maverick, reformer, and patriot — that unites and justifies his campaign? Will Mr. Obama be able to reignite the inspiration of his campaign without overreaching into self-absorbed, second-rate Ted Sorensen? Will he be able to define an idealism that offers something more than himself as the ideal?

Even after his worst few weeks of the general election campaign, Mr. Obama remains in the lead. And he remains a far more talented and compelling figure than either John Kerry or Al Gore. Mr. McCain still swims upstream, but the current may run weaker than we thought.

© 2008 Washington Post Writers Group