The outcome of the 2008 election is going to depend almost entirely on the facts on the ground in Iraq -- or, rather, on American public perception of those facts. And it should.

As long as most Republicans want to fight and win the war in Iraq, a conflict they see as the irrefutable central front in the global war on terror, while most Democrats want to cut and run, then the American people are faced with one prohibitively important decision.

The global war on terror, while often referred to as a new or different kind of war, is shaping up to share several similarities with the Cold War. The opponents are not nations, exactly, but two fundamental, irreconcilable philosophies. On one side is Western, capitalistic, democratic liberalism, tolerant of and sustained by scientific and philosophical curiosity and informed by Judeo-Christian values. On the other side is theocratic, dictatorial Islamic fundamentalism, by definition intolerant of scientific or philosophical inquiry (let alone dissent). It is not simply informed by the Quran but insistent upon obedience to Sharia law, including its terrifying demands for unending, violent jihad against anyone who refuses to bow to Muhammad's 7th-century proposition, "Submit or die."

Considering the war on terror thusly, why would anyone show more than passing interest in Rudy Giuliani's flat tax or Hillary Clinton's "national conversation"? You want two Americas, John Edwards? How about these: the one we live in now, imperfect but freer and more prosperous than any nation on Earth, or the one we'll inhabit in 40 years if we stop fighting the terrorists, convert to Islam and start honor-killing our daughters and fitting our wives for burqas.

The election of 2008 will be an election about the war. If the surge continues to work and Iraq becomes stable and Iraqis are able to take on more of their country's security responsibilities, then Republicans supporting the war will not only be able to ride the war's inevitable increased popularity wave but also throw Democrats under a bus for being sunshine soldiers when the going got tough in 2006 and 2007.

On the other hand, if Speaker Nancy Pelosi and the Democrat Congress are successful in undermining the commander-in-chief (thereby emboldening the terrorists to kill more Americans in Iraq) and the media continues its relentless drumbeat of bad news, then Republican "win at all costs" rhetoric will be less attractive to voters tired of their sons dying halfway around the world.

Despite the continued unpopularity of the war's progress -- or, more to the point, its lack thereof -- Republicans are still on more solid ground than Democrats. First of all, there is a Republican position on the war: Win it. If we do win, Republicans in general, and President Bush in particular, will benefit greatly.

Democrats, on the other hand, are still hesitant even to admit there is a war on terror (they won't even use the term!), let alone provide specifics about their actual national security policies. Sens. Barack Obama (D-Ill.) and Clinton (D-N.Y.) have thus far been running essentially content-free, personality campaigns (a far more defensible strategy for Obama, whose personality may actually serve as an asset).

But that won't do forever. Come 2008, someone is going to have to stand up for the Democrats and explain to the American people that either: a) "Yes, we're at war, and here's how we're going to win it," and thus lose his base, or b) "No, we're not at war, and try to forget about the big hole in Lower Manhattan," and thus lose independents.

If things go well in Iraq, neither option will work; if they don't go well, … let's just say if I were a Democratic strategist, I'd still be looking really hard for a Plan C.