Dan Balz, one of America's finest political reporters, wrote this on his Washington Post blog yesterday:

The most important decision Barack Obama will make between now and the November election is the selection of a vice presidential running mate. That makes all the more remarkable his effort Tuesday to suggest that the people he has put in charge of helping make the decision are somehow not really part of his campaign.

Obama is on the defensive over his selection of James A. Johnson, the former CEO of Fannie Mae, to help lead the vice presidential search process, a role he played for John F. Kerry four years ago.

Johnson is drawing fire over his jumbo home loans from Countrywide Financial, a major actor in the subprime mortgage mess, that may have been below market rates.… It isn't clear whether the uproar over Johnson is a passing storm or a more serious problem for the Obama campaign… But the candidate's response has raised questions about the candidate himself that could well linger past the moment.

After Balz's piece appeared it was announced that James Johnson will be leaving his post at the Obama campaign. Throwing Johnson under the same bus that rolled over the Reverend Jeremiah A. Wright Jr. and Trinity Church may be politically necessary. Yet the damage, I think, is real because of an accretion effect.

It can't be said often enough: the conceit of the Obama campaign is that its candidate is the antithesis of politics as it has been practiced for decades, if not for centuries. He is, we are told, the agent of change, the great turner of the page, a man unstained by politics and who will alter the way it has been practiced. He is bi-partisan and post-partisan and beyond political labeling. He will not unfairly portray the views of his opponent or engage in petty distractions. According to his wife Michelle, he will heal the broken souls of America. And according to Obama himself, he will begin to heal the planet.

The bar has been set enormously high — and it has been set there by Obama, his wife, and his campaign.

If voters begin to believe that the Obama Phenomenon is really an Obama Myth — that he is just another conventional politician, but in this instance one who emerged out of the largely polluted waters of Chicago politics — then Obama is reduced to being a one-term senator with very few achievements in his life that commend him to be president. He also happens to be the most liberal candidate for president since George McGovern. We are now in the early phase of that transformation; it remains to be seen if it continues or if Obama can find a way to arrest or even reverse it.

Obama still has things working in his favor, from a horrible political environment for Republicans, to a first-rate campaign to enormous fund-raising abilities, to some very impressive political skills. But Obama's now-apparent weaknesses may prove to be debilitating.

Barack Obama will be the focal point of this election. If Americans find him to be an acceptable choice for president, he will probably win, given all the factors that are working in his favor. But if the doubts that have persisted about him begin to grow and metastasize — if large numbers of Americans come to believe that the Obama appeal is, at its core, a mirage — then McCain has a real chance to prevail. And if he does, the Democratic party and liberalism will have a nervous breakdown unlike any we have seen.

Democrats remain hopeful, but they are also beginning to harbor some doubts and even fears. This may not be as easy as they thought.

Stay tuned.

— Peter Wehner, former deputy assistant to the president, is a senior fellow at the Ethics and Public Policy Center.