It used to be said that American politics ended "at the water's edge." Politicians and parties would fight tooth and nail over domestic issues, but when the president (as commander-in-chief) deployed troops overseas, Congress (as the branch in charge of spending) would make sure those forces had the resources to win.

Unfortunately, that all-together-now spirit is dissolving.

In February, the House of Representatives passed a nonbinding resolution opposing the Bush administration' s surge strategy for Iraq. Being "nonbinding," the vote was essentially meaningless. Still, it was only the first skirmish in what likely will prove a bitter struggle over the future of U.S. policy in Iraq.

House Democrats engineered a 246-182 vote on the anti-surge resolution by crafting a resolution that enabled House members to take a cost-free symbolic stand against President Bush's "new way forward" without taking responsibility for proposing a coherent alternative policy. In part this is because Bush's congressional critics could not agree on an alternative policy, so they voted to support a lowest-common-denominator criticism of current policy.  One could almost call it the "irresolution resolution."

Alone, such a vote would stand as an unusual -- and heavily hedged -- wartime rebuke to the nation's commander-in-chief. But there's more to come from this Congress. Pressured by supporters in the ultra-liberal "netroots," congressional Democrats have taken only the first step in what will be a protracted campaign to hamstring Bush's Middle East policy and undermine his constitutional authority.

At stake is not only the fate of Iraq but also the outcome of the war against terrorism and of U.S. efforts to contain Iran, as well as the ability of future American presidents to fight and win wars.

House Democrats already have signaled their intent to escalate efforts to block the administration's plans in Iraq by restricting the funds and resources needed to implement its new counter-insurgency strategy.

Rep. John Murtha, D-Pa., chairman of the House Appropriations Subcommittee on Defense, says he will seek to attach conditions to the $93 billion supplemental defense appropriation due to be voted on this month. Murtha's restrictions would make it impossible for the administration to follow through with its promising new strategy.

Murtha intends to impose restrictions on the deployment of military units to Iraq by stipulating that they must meet certain requirements for equipment, training and time between deployments. By cynically masking his proposals as efforts to enhance military readiness, Rep. Murtha seeks to sabotage the surge strategy.

Democrats hope to sidestep the charge that they are undermining the troops during wartime by imposing restrictions on military management decisions rather than by directly cutting funds to support operations. But blocking reinforcements could put the lives of the troops already deployed in Iraq at greater risk. And those troops now in Iraq likely will face extended war-zone service if Congress delays the deployment of their replacements. So much for supporting the troops.

This kind of congressional micromanagement not only undermines the flexibility of the forces available to military commanders and reduces the overall effectiveness of the war effort, it impinges on the president's powers as commander-in-chief. Such legislation could provoke a constitutional clash over presidential war powers. What happened to politics stopping at the water's edge?

If it undercuts the administration's Iraq policy, Congress risks fatally undermining the fledgling Iraqi government, allowing that nation to slide into a much bloodier sectarian civil war and handing Iran, Syriaand al-Qaeda a major victory. If Congress insists on choking off the troop reinforcements and resources needed to implement the Bush administration's Iraq strategy, it should at least assume responsibility for the disaster likely to result.

A rush-to-exit strategy would risk abandoning Iraqis to a humanitarian catastrophe far worse than the murderous ethnic cleansing in the Balkans that led to two U.S. interventions there in the 1990s. It likely would eclipse even the tragic bloodletting in Darfur today.

Pulling the plug on the war in Iraq also would help create the conditions for many future wars. A defeat in Iraq would increase the likelihood that future U.S. military interventions will be needed to combat a resurgent al-Qaeda, contain spillover effects that threaten Saudi Arabia, Kuwait and Jordan, and confront an increasingly aggressive Iran.

For generations, Americans have understood that political leaders -- and their parties -- don't fight wars. Countries fight wars. And, to paraphrase Abraham Lincoln, a country divided against itself isn't likely to win its wars.

James Phillips is Research Fellow for Middle Eastern Affairs in the Douglas and Sarah Allison Center for Foreign Policy Studies, a division of the Kathryn and Shelby Cullom Davis Institute for International Studies, at the Heritage Foundation.