As expected, the 2006 elections were a referendum on President Bush's Iraq policy. Leading Democrats, from Nancy Pelosi to Hillary Clinton, pointed to the election results as a mandate for change, especially a change of course in Iraq. But a change in what direction? Six of every 10 respondents in some exit polls favor a withdrawal of some or all troops from Iraq. Voter sentiment, however, will not have a major impact on U.S. policy in Iraq unless Democrats are willing to get behind an exit strategy and rally Republican support for a withdrawal plan.

In fairness, this is no simple task. Public dissatisfaction over the war in Iraq paved the way for the Democrats' return to power in Congress, but that doesn't signal a nationwide embrace of core Democratic principles.

The voters did not vote for a Democratic plan on Iraq -- there wasn't one. Democratic candidates for office did not speak with one voice on what should be done. Now leaders of the Democratic Party must scramble to fashion a consensus around a single alternative Iraq policy that can attract broad public support.

But change will not be driven solely by Democrats. The Republican Party consensus around "stay the course" collapsed weeks before voters went to the polls. GOP candidates tried to localize the elections by putting rhetorical distance between themselves and the president's policies, but the defeat of many popular Republican incumbents shows that such efforts were largely unsuccessful. Indeed, in a bitter irony, two Republicans who bucked the president in October 2002 by voting against the Iraq war -- 15-term Iowa Rep. Jim Leach and Rhode Island Sen. Lincoln Chafee -- went down in defeat.

The fate of these moderate voices will be a cautionary tale for Republicans struggling to cope with their new status as the minority party on Capitol Hill. Some Republican incumbents who survived the onslaught, as well as the handful of new Republican members who managed to win despite the anti-Iraq-war headwind, are likely to put still more distance between themselves and the president, particularly on the war issue. In short, new ideas and new energy for a change of course in Iraq can be expected to be heard from both sides of the aisle.

Congress cannot change Iraq policy, but it can shape the parameters of the debate. New committee chairs are likely to use their subpoena powers to convene hearings into the Bush administration's conduct of the war. This is long overdue. The war has not progressed as advocates predicted it would. The costs have far exceeded prewar estimates, and the prospective benefits remain speculative, at best. Most importantly, the administration has no credible military or political strategy in Iraq. Victory is a goal, not a strategy for achieving that goal. The administration must explain the costs and risks of the current U.S. mission.

But while a full public accounting is necessary, it is not sufficient. Public hearings may cast light on past mistakes, but they rarely illuminate a clear path forward. Advocates for a change of course in Iraq must fashion a broad bipartisan consensus, consistent with the wishes of the American people, that will terminate the U.S. military presence there by a date certain. Within the parameters of this consensus, we can expect to see competing proposals for how this should be done. The debate will include not simply how fast the troops should be withdrawn, but also what measures can be taken to avert the worst-case scenarios that could ensue in Iraq.

The new emphasis will be on limiting the damage to American interests and security. The new leaders must also figure out how to explain that withdrawal will be costly and messy, but that the fault for this situation lies with the administration, which defied the Powell Doctrine and invaded with underwhelming force and no exit strategy.

Withdrawal carries many risks, but after 3 1/2 years of war, with no end in sight, we are forced to choose from a set of unpalatable options. Given strong public support for a timeline for the withdrawal of U.S. troops from Iraq, we can expect the debate to shift from whether we should leave to how we will leave. Before Tuesday's elections, such a dramatic change of course seemed unlikely. After the elections, "stay the course" is even more unlikely.

Christopher Preble is director of foreign-policy studies at the Cato Institute and a founding member of the Coalition for a Realistic Foreign Policy. He is the author of Exiting Iraq: Why the U.S. Must End the Occupation and Renew the War Against al-Qaida.