The presidential campaign ended on November 4, but there was a moment several weeks before when I thought to myself: "McCain doesn't stand a chance."

It wasn't one of the presidential debates, as enlightening as they were. Nor was it during those weeks when it appeared our economic system was on the verge of collapse.

It was the moment I saw the first "Joe the Plumber" advertisements that the McCain campaign produced after then-Senator Obama's famous interaction with a man calling himself Joe at a campaign stop.

You might recall the ad: it featured a montage of different men and women, each proclaiming they were "Joe the Plumber" and they were concerned about Obama's throw-away line on "sharing the wealth."

Leaving aside for the moment that Joe the Plumber was neither a registered plumber nor named Joe, the fact that the McCain campaign glommed onto an incident that deserved no more than a few hours of media time and turned it into a center piece of the closing weeks of the campaign reinforced for me one of the fundamental problems for McCain—the lack of a single, understandable message.

When Sen. Obama began running for president almost two years ago, he picked one theme and stuck to it even up to his first speech as president-elect: "change." One can certainly argue whether the change Mr. Obama represents is a good thing or a bad thing, but whatever your personal view, Obama successfully branded himself as "change" at a time when that is exactly what many Americans wanted.

Compare that to Senator McCain. Variously over the months his campaigned theme bounced from "war hero," to "experience," to "maverick," to "Country First," to "Joe the Plumber." He even tried "change." His attacks on Obama suffered the same multiple personality disorder, identifying the Democrat as "celebrity," "liberal," "inexperienced," "socialist," and even "friend of terrorists." None of them stuck.

As a consultant in marketing and public affairs, I often tell my clients that many months, and sometimes years, of consistent and repetitive communication around a single key message is required before the public will truly come to understand and internalize what your organization or product stands for. This is as true for presidents as it is for products.

Mr. Obama had a clear and understandable message and he pounded it day in and day out for almost two years. By the end, Americans felt they knew what he stood for.

Mr. McCain, unfortunately, tried multiple messages, which in effect meant he had no message. By the time "Joe the Plumber" rolled around, it hit me—the McCain campaign is making itself up as it goes along. The results speak for themselves.

Some people dislike the idea of "selling" a president with a brand, the way Procter&Gamble sells detergent, but there is nothing wrong or cynical about positioning a political candidate this way. A brand needs to be based upon the truth. Voters, like consumers, will eventually see through false claims or reject brand messages that are too complex and ever-changing.

Earlier this year, when it became evident that Obama and McCain would be the candidates, I recall a sense of optimism from many people that the nation had two skilled and honorable men running for president. At that point, either could have won. The fact that Obama did so decisively is a testament to the power of his message and the discipline of its delivery.

For McCain, Joe the Plumber might have been able to fix his sink, but he couldn't fix his campaign.