Under George W. Bush we’ve wasted billions of dollars on a war in Iraq, while we’ve ignore our economy and infrastructure at home. The world is moving forward, but we’re going backwards.

Tom Friedman went to China during the Olympics, and he was struck by incredible progress made by the Chinese in such a short period of time. Meanwhile, we’re asleep at the switch.

The difference is starting to show. Just compare arriving at La Guardia’s dumpy terminal in New York City and driving through the crumbling infrastructure into Manhattan with arriving at Shanghai’s sleek airport and taking the 220-mile-per-hour magnetic levitation train, which uses electromagnetic propulsion instead of steel wheels and tracks, to get to town in a blink.

Then ask yourself: Who is living in the third world country?

Yes, if you drive an hour out of Beijing, you meet the vast dirt-poor third world of China. But here’s what’s new: The rich parts of China, the modern parts of Beijing or Shanghai or Dalian, are now more state of the art than rich America. The buildings are architecturally more interesting, the wireless networks more sophisticated, the roads and trains more efficient and nicer. And, I repeat, they did not get all this by discovering oil. They got it by digging inside themselves.

I realize the differences: We were attacked on 9/11; they were not. We have real enemies; theirs are small and mostly domestic. We had to respond to 9/11 at least by eliminating the Al Qaeda base in Afghanistan and investing in tighter homeland security. They could avoid foreign entanglements. Trying to build democracy in Iraq, though, which I supported, was a war of choice and is unlikely to ever produce anything equal to its huge price tag.

But the first rule of holes is that when you’re in one, stop digging. When you see how much modern infrastructure has been built in China since 2001, under the banner of the Olympics, and you see how much infrastructure has been postponed in America since 2001, under the banner of the war on terrorism, it’s clear that the next seven years need to be devoted to nation-building in America.

We need to finish our business in Iraq and Afghanistan as quickly as possible, which is why it is a travesty that the Iraqi Parliament has gone on vacation while 130,000 U.S. troops are standing guard. We can no longer afford to postpone our nation-building while Iraqis squabble over whether to do theirs.

A lot of people are now advising Barack Obama to get dirty with John McCain. Sure, fight fire with fire. That’s necessary, but it is not sufficient.

Obama got this far because many voters projected onto him that he could be the leader of an American renewal. They know we need nation-building at home now — not in Iraq, not in Afghanistan, not in Georgia, but in America. Obama cannot lose that theme.

He cannot let Republicans make this election about who is tough enough to stand up to Russia or bin Laden. It has to be about who is strong enough, focused enough, creative enough and unifying enough to get Americans to rebuild America. The next president can have all the foreign affairs experience in the world, but it will be useless, utterly useless, if we, as a country, are weak.