Why did Obama feel the need for this speech?

Washington Post:

Dogged by persistent questions about his faith in God and country, Sen. Barack Obama today journeyed to Harry Truman's birthplace to lay out his vision of patriotism, conceding that he has learned in this campaign "the question of who is -- or is not -- a patriot all too often poisons our political debate."

"Throughout my life, I have always taken my deep and abiding love for this country as a given, " Obama said. "It was how I was raised. It was what propelled me into public service. It it why I am running for president. And yet at times over the last 16 months, my patriotism [has been] challenged - at times as a result of my own carelessness, more often as a result of the desire by some to score political points and raise fears about who I am and what I stand for."

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I don't know that he has been dogged by other candidates on this issue although some voters have raised questions about his dedication in this area. I think much of it comes with the territory of being a liberal.

There are just too many liberals who want to define patriotism as running down your country and not caring for the symbols of patriotism, be they the flag or the pledge of allegiance. Obama's lack of any military experience makes him especially vulnerable because he has had no training in showing respect for the flag and the pledge or the national anthem.

As Nixon found out, when you have to give a speech saying I am not a crook you have a problem. I think the same can be said for Obama's need for this speech today. His little spiel about the absence of his lapel pin was too revealing. Now he wants to be president bad enough to wear one. It is not quite a death bed confession of faith, but it is close.