After months of mudslinging and hundreds of millions of dollars spent on ads, the presidential election has come down to a single question. How you and I and our neighbors and friends answer that question will decide who wins the White House.

Here’s the question: Do you believe the Iraq war is a diversion from the war on terror, or do you believe it’s a vital front?

If you are sure it’s a diversion, we’ll count you as a John Kerry voter.

If you believe Iraq is a necessary part of the larger war on terror, you go to President Bush’s column.

To those who haven’t decided yet, we offer membership in the fence-sitters’ club and some fortune-cookie wisdom: He who sits on fence gets splinters.

But don’t despair, for this is one of the toughest decisions American voters have ever had to make. Indeed, this is only the seventh time in our history that a presidential election has come during a war.

By the way, disaster looms if the man we elect turns out to be wrong.

So the single question before us is hardly simple. Here’s how I have arrived at my answer. Like Kerry, I reserve the right to change my mind.

Start with Bush’s position, which is that the war is necessary and he would invade Iraq all over again. He says that even though there were no weapons of mass destruction and no evidence of operational ties between Saddam Hussein and Osama Bin Laden, America is safer with Saddam in prison and the war is worth the blood and treasure.

Kerry mocks the president on this, saying last week, “Can he possibly be serious?”

Give Kerry points. Bush would not have gotten congressional and public support for the war if everyone had known then what we know now. Certainly, Britain wouldn’t have signed on.

Without the fear of Iraq’s weapons, how would Bush have sold a pre-emptive war? “Iraq might become a threat” doesn’t ring the same alarm bells as the insistent claim, backed by the CIA, that Saddam had nuclear, chemical and biological weapons and was likely to give them to bin Laden. In fact, Bush has to say he’d do it all again because to admit otherwise would be a calamity for the troops and for him. But even he couldn’t sell an invasion knowing what he knows now.

So then Kerry is right, right? Iraq is just a diversion, a costly mistake that has taken our eyes off the real terrorists, and we must look for ways to get out.

Whoa, Nellie. This is where it gets tricky. It’s tricky because Iraq, in key ways, has become the very place Bush said it was – even though it wasn’t that way when he said it was.

Got that? Try this:

Iraq has become a haven for terrorists. Many are foreigners with ties to al Qaeda. That makes Iraq a direct threat to the United States that must be confronted.

For example, Prime Minister Iyad Allawi said last week that 30 percent of the insurgents are foreign jihadists who see Iraq as the battleground against the West.

While the true percentage may be lower, Islamic fanatics from around the world are in Iraq. Abu Musab al-Zarqawi, the Jordanian behind the hostage beheadings, is linked to bin Laden. Muslim fundamentalists in northern Iraq, like bin Laden, have declared war on all Christians and Jews – anywhere in the world.

Now imagine the damage to the war on terror if America suddenly quit Iraq, as many Democrats urge. Iraq would become a Taliban-like theocracy, and terrorists everywhere would view us as soft – and be emboldened to strike. Weaker countries would cut deals with them, tripping a chain reaction of appeasement that would turn back civilization’s clock.

That’s my answer. Iraq was a mistake to start with, but it isn’t now. For military and psychological reasons, it has become a vital front in the war on terror. And we must prevail there – or fight them here.