The economic news is so bad that it’s no wonder Sen. Barack Obama is leading the presidential race. But he is giving political gifts to Sen. John McCain on Iraq policy.

Every voter understands the simple principle that you don’t make up your mind about something until you have checked the facts — but this week Obama declared he will stick to his predetermined troop-withdrawal schedule no matter what he might learn on his forthcoming trip to Iraq.

The only reasonable explanation for his rigidity is that he’s hemmed in by the overwhelming demand of the Democratic base — and left-wing bloggers above all — that he not backtrack on the central promise of his campaign: to end the war.

A new Quinnipiac poll shows that a majority of likely voters — 51 percent to 43 percent — opposes immediate withdrawal from Iraq or setting a fixed deadline. But 64 percent of Democrats favor one or the other.

No one knows exactly what happened between Obama’s first news conference on July 3, when he said he might “refine” his withdrawal schedule after visiting Iraq, and his hastily called second news conference, but the likelihood is that he feared getting blasted from the left, like he did after shifting on terrorist surveillance.

Obama seems as locked in ideologically on Iraq as McCain is on economics. President Bush’s tax-cut-and-borrow strategy has ballooned the federal debt from $5 trillion to $8 trillion without helping workers’ incomes — yet McCain is determined to extend all the tax cuts he once opposed. Why? Because the Republican base demands it.

And McCain is suffering for it. According to the Washington Post/ABC poll, Obama is favored over McCain on economic issues — which rate No. 1 in voter concerns — 54 percent to 35 percent. McCain hasn’t escaped Obama’s charge that he represents “Bush’s third term,” and Obama still hasn’t begun to employ Ronald Reagan’s killer question from 1980, “Are you better off now than you were … ?”

On Iraq, however, the Post poll gives a slight edge to McCain, 47 percent to 45 percent, and this was before Obama’s mistakes this week.

Besides holding to his 16-month withdrawal deadline without talking to Gen. David Petraeus or Iraqi Prime Minister Nuri al-Maliki, Obama missed another huge opportunity to demonstrate mastery of foreign policy and genuineness in politics.

He could have said, in his opinion piece in the New York Times on Monday and his foreign policy speech on Tuesday: “I acknowledge, I was wrong to oppose President Bush’s surge in Iraq last year. It has worked. In fact, it has worked so well that we can now safely withdraw from Iraq and transfer forces to Afghanistan, the central front in the war on terrorism.”

But he couldn’t bring himself to admit that he was wrong about the surge, which has manifestly reduced violence and has opened the way for significant Iraqi political and military progress.

As the State Department reported this month, the Iraqi government is making progress on 15 of the 18 political benchmarks set for it by Congress. A majority of Iraqi provinces are now the military responsibility of Iraqi forces.

Obama, while tipping his hat to the performance of the U.S. military, continued to dismiss any evidence of political progress. He and aides act as though the Sunni turn against Al Qaeda in Iraq and the government’s suppression of Shiite militias just happened — neglecting the security provided by the surge.

Obama’s tack, if persisted in after his trip, opens him up to potentially devastating McCain commercials using Obama on videotape predicting that the surge would fail alongside Iraqi testimonials that it was essential to free their country from Al Qaeda atrocities.

Obama was wrong to say that Iraq “is not and never was the central front in the war on terrorism.” It certainly was, for awhile, when Osama bin Laden was urging Islamicists to go there to achieve martyrdom killing Americans.

But now — with Al Qaeda largely neutralized in Iraq — Afghanistan and Pakistan once again become the central front. It’s appropriate that the two presidential candidates have turned their attention to that theater, and it’s encouraging that their policies are a similar combination of military power, aid and diplomacy.

But while Americans tend to regard Afghanistan as a “good war” worth fighting, they have no idea how complex it is — with a central government that controls only the capital, endemic corruption, narcotics trafficking bringing $8 billion a year into Taliban coffers, a terrorist safe haven in Pakistan (whose government can’t control its own territory) and a divided NATO command without enough troops.

The private intelligence firm Stratfor published an analysis this week declaring that “Afghanistan appears to have become a magnet for foreign fighters again. Uninhibited access to Pakistan as a safe haven … will make it impossible to contain the escalation” of fighting, up 50 percent in June.

Taliban Web postings, the report said, “indicate their intent is to overrun a NATO outpost in the style of the French loss in 1954 at Dien Bien Phu in Vietnam, so as to cause embarrassment and collapse of support on the NATO home fronts, as well as in Afghanistan.”

On the basis of their public statements, both McCain and Obama intend to be “war presidents” for the foreseeable future. McCain wants to transfer the counter-insurgency strategy that’s worked in Iraq to Afghanistan. Obama does not acknowledge that counter-insurgency has worked.

And then, there’s the question: Will the Democratic left allow Obama to pursue a vigorous war in Afghanistan?

Already, in The Nation magazine this week, antiwar activist Tom Hayden wrote that “any proposal to transfer American troops from Iraq to Afghanistan and Pakistan is sure to cause debate and questions among peace activists and rank-and-file Democrats. The proposal potentially represents a wider quagmire for the U.S. government and military.”