Supporters: Sen. John McCain, The Weekly Standard, Gen. Anthony Zinni

The argument: Dramatically increase the number of U.S. ground troops in Iraq without a specific timeline for withdrawal. It’s a belated attempt to make amends for not having enough boots on the ground in the first place.

Drawbacks: There just aren’t enough U.S. soldiers available. The plan would mean extending tours of duty (again) and calling up more overstretched National Guard brigades. It would also impair America’s ability to respond to a growing insurgency in Afghanistan.

Chance of being adopted: Zero. Without the necessary troops, the plan looks dead on arrival.

Supporters: The Joint Chiefs, the Iraq Study Group

The argument: Iraq is too important and fragile to leave precipitously. By surging the number of U.S. troops for a brief period while shifting combat brigades to training and advisory roles, the United States can stabilize the situation enough to prevent a complete disaster. A commitment to stay on longer, even in a diminished role, would bolster the shaky Iraqi government.

Drawbacks: If U.S. troops shift roles before the Iraqis are ready to step up, al Qaeda and Shiite militias will fill the vacuum. With the American public’s patience wearing thin, time may be the one thing the U.S. military doesn’t have.

Chance of being adopted: High. It’s the most palatable plan both to generals who have few troops left and to congressional leaders, who neither want to stay the current course nor call for immediate withdrawal.

Supporters: Former Iraqi Prime Minister Ayad Allawi, U.S. Ambassador Zalmay Khalilzad, Iraq’s Sunni neighbors

The argument: Baathists and tribal sheikhs in the Sunni insurgency are pragmatists, not ideologues. By giving them amnesty, a rollback of de-Baathification, and a fair share of oil revenues, the United States could theoretically split the insurgency by creating a cleavage between Sunnis and al Qaeda. And because the United States has inadvertently played midwife to Iranian ambitions by destroying the Iraqi Army and empowering the Shia through elections, a Sunni tilt might reassure the 85 percent of the Arab world that is Sunni.

Drawbacks: Negotiating with Sunni insurgents could create a Shiite backlash against the United States, strengthening the hand of anti-American Shiite leaders like Moqtada al-Sadr and weakening Prime Minister Nuri al-Maliki’s government. Plus, it won’t be easy to separate the insurgency into neat boxes, or determine who speaks for the Sunnis.

Chance of being adopted: Low. Americans have negotiated with the insurgents in the past without much success, and recent reports suggest this strategy is being abandoned altogether.

Supporters: Vice President Dick Cheney, Iraqi Shiite leader Abdel Aziz al-Hakim

The argument: Civil wars can last decades and usually end only when one side wins a decisive military victory. Instead of policing a civil war, the United States should either follow a policy of noninterference, or fight only the Sunni insurgency.

Drawbacks: Choosing whom to back on the Shiite side could worsen intra-Shia rivalries. It would also alienate Iraq’s Sunni neighbors while strengthening Iranian influence in Iraq. And it could mean the slaughter of Iraq’s Sunni population, whose flight to neighboring countries might further destabilize the region.

Chance of being adopted: Medium to High. It wouldn’t be a dramatic change of course—siding with the Shia is the path of least resistance.

Supporters: Democratic Rep. John Murtha, Iran, Syria, most Iraqis

The argument: The longer the United States stays, the worse Iraq gets. Not only do most Iraqis want the Americans out, but the U.S. presence may be exacerbating the sectarian violence and preventing Iraqis from reconciling with each other. After leaving, the United States would retain “over the horizon” capability via its bases in the Persian Gulf if vital interests are threatened.

Drawbacks: Although al Qaeda would declare victory, a U.S. pullout would actually leave most of Iraq in Iranian hands. Nervous Sunni states in the region might then intervene to protect their coreligionists. The result: a bloodbath and sky-high oil prices.

Chance of being adopted: Moderate. President George W. Bush has invested too much political capital in the war to perform such a dramatic public U-turn. But U.S. troops must leave eventually, and the Iranians will still be there when they do.

Supporters: The Iraq Study Group, congressional Democrats, the U.S. foreign-policy establishment

The argument: Iran and Syria were happy to see the United States get a bloody nose in the early years of the insurgency, but they now have an interest in a stable Iraq. Stability will elude the region as long as Iraq is in chaos.

Drawbacks: With a humiliating U.S. withdrawal in sight, the Iranians and Syrians have no incentive to negotiate—unless the price paid is very high.

Chance of being adopted: Low. The Bush administration may make token gestures in this direction, but it won’t grant the painful concessions that Iran and Syria will demand. There may be a regional conference, but don’t expect too many kind words being exchanged.

Supporters: Democratic Sen. Joseph Biden, Leslie Gelb, radical Kurds and Shia

The argument: Divide Iraq into three autonomous regions—one each for the Shia, Sunni, and Kurds—with a limited central government that distributes oil revenue by population. The Kurds already have an autonomous region in the north, and some Shia factions are busy carving out their own “Shiastan” in the south. With their own region and guaranteed oil revenue, wary Sunnis can be convinced they have a stake in the new Iraq.

Drawbacks: Such a plan might exacerbate ethnic cleansing in mixed areas. The oil-less Sunnis fear being left with nothing by vengeful Shia and Kurds, and the United States is hardly a trusted guarantor. Along with the nationalistic Sadr movement, Sunnis reject federalism as a foreign plot.

Chance of being adopted: Moderate. Federalism is permissible under the current Iraqi constitution, but opposition is fierce among Iraqi nationalists. Advocates counter that it simply formalizes a process that is already under way.