Elections are supposed to decide things, but often they trigger a new debate over exactly what the voters decided. Among Washington politicos, the battle to interpret election results can be as fierce as the campaigns themselves.

November's midterm election is an exception. Most observers agree on the basic plot line: The political center abandoned the Republicans because the Republicans had abandoned the center.

The GOP lost because it put conservative ideology and belligerent partisanship over the prosaic business of governing effectively. Instead, the Bush Republicans produced the mess in Iraq, profligate spending, economic inequality and the worst scandals since the Grant administration. Moderate and independent swing voters accordingly turned thumbs down on the highly polarizing approach to politics crafted by White House political consigliere Karl Rove and GOP lawmakers.

Prematurely declared dead by pundits and partisan warriors, swing voters came out swinging with a blunt message for Washington's political class: "Polarize this!" Republican incumbents bore the brunt of their wrath, but the vote was also a rebuff to liberal activists who have been demanding that Democrats pursue a left-leaning version of Rovian polarization.

Instead, winning candidates took aim at the rabid partisanship that has overtaken Washington. Emblematic were the campaigns of California Gov. Arnold Schwarzenegger and Connecticut Sen. Joe Lieberman. After a disastrous lurch to the right in 2005, the gubernator pledged to govern from the center and cruised to re-election as a Republican in an overwhelmingly Democratic state. Now he's urging national Republicans to embrace the "California way" by putting centrist problem-solving over pandering to the party's base of religious conservatives. In Connecticut, Lieberman withstood a punitive expedition by anti-war activists and left-wing bloggers to hold his Senate seat after narrowly losing the Democratic primary to Ned Lamont, a wealthy liberal. Lieberman stressed the theme of "progress, not partisanship," while Lamont channeled the spirit of Howard Dean's 2004 presidential campaign by making strident opposition to the Iraq war the singular litmus test of Democratic authenticity.

So although President Bush was not on the ballot, the formula that political journalists John Harris and Mark Halperin call "Bush Politics" was the big loser in 2006 (see Clinton Politics vs. Bush Politics). This approach aims at solidifying and energizing the conservative base, while using terrorism and taxes as wedges to split Democrats and pick off enough centrist voters to build a bare majority. Where "Clinton Politics" tried to bridge differences, write Harris and Halperin, Bush Politics seeks to clarify them and present the voters with stark political choices. This polarizing strategy appeared to work like a charm in 2002 and 2004, leading credulous pundits on all sides to declare that swing voters no longer mattered. They also hailed Rove as the prophet of a new era of ideological politics.

Costly failures. Rove discerned in those two elections a "rolling realignment" that would cement a new conservative majority after a long period of parity between the parties. But the Republican juggernaut stalled and rolled backward in 2006, mostly because its main fuel supply -- the party's huge advantage on national security -- evaporated. That's the other big story of 2006: The Bush administration's costly failures in Iraq seem finally to have broken the spell cast on U.S. politics by the 9/11 terror attacks.

Those attacks, not Rove's alleged political genius, transformed the Bush presidency. Recall that Bush limped into office despite having lost the popular vote and, by late summer of 2001, was viewed favorably by only half the country. Then came 9/11. The public, as it always does when the country is attacked, rallied powerfully around the commander in chief. By October 2001, the president's approval rating had zoomed to 90 percent. Bush soon shed his humble, uniter-not-a-divider persona and recast himself as an American Churchill, summoned by destiny to lead the nation in an epochal struggle against evil.

Rather than keep the country united, however, the president used his elevated public standing to score partisan political points. During the 2002 election, for example, the White House seized on a peripheral dispute over job protections at the proposed Homeland Security Department (which Bush had initially opposed) to portray Democrats as soft on security. Politicizing national security helped Republicans stave off the usual midterm losses, but it incensed Democrats, who, having strongly supported the president's war on terror, felt that they had been played for suckers.

At first, Bush and Rove reaped big political gains by exploiting Democrats' post-Vietnam reputation for foreign policy weakness. After 9/11, this national security confidence gap widened into a chasm, with the public choosing Republicans by 20- and 30- point margins when asked which party they trusted to protect the country against terrorism. But three years of cascading violence in Iraq finally caught up with the Republicans in 2006. Solid majorities of voters disapproved of the president's handling of Iraq and believed that the war had failed to make Americans safer. The GOP's edge on fighting terrorism dwindled to just 5 percentage points, while a bare majority of voters for the first time expressed confidence that Democrats could do the job.

Oddly enough, Bush also insisted on making Iraq the central issue in 2006. Even as GOP candidates tried to squirm out of the unpopular president's embrace and distance themselves from his Iraq policies, Bush stumped the country warning that a Democratic victory would mean a U.S. defeat in Iraq. "However they put it," Bush said in Georgia, "the Democratic approach in Iraq comes down to this: The terrorists win and America loses." This time, however, Americans weren't buying the White House's increasingly frantic efforts to conflate Iraq and the war on terror.

For their part, Democrats seem to recognize that they have won a hearing on national security, not a mandate to get America out of Iraq as quickly as possible. That was one reason House Democrats rejected the post-election bid of Rep. Jack Murtha (D-Pa.) for House majority leader. The new Democratic majority, of course, is determined to restore congressional oversight of the executive branch. But with control of Congress also comes the responsibility to move beyond mere criticism and forge a coherent Democratic position on Iraq. Yet it also means Democrats must be willing to negotiate with the White House on a bipartisan approach that puts America's security over finger-pointing. At the same time, Democrats should avoid the pitfall of reducing the security debate entirely to Iraq. Their greatest challenge, heading into 2008, is to begin laying out a distinct alternative to Bush's war on terror -- for combating jihadist extremism, containing Iran's hegemonic ambitions, and stopping the spread of weapons of mass destruction.

Their own hyper-partisanship also backfired on congressional Republicans in 2006. Although their control of Congress rested on a slender margin, GOP leaders behaved as though they commanded a huge majority. They made committees more lopsidedly partisan, rarely allowed Democrats to present legislative alternatives, froze them out of House-Senate conferences and adopted the "Hastert rule," named after Speaker Denny Hastert (R-Ill.), which said that no measure could go to the floor of the House without the backing of a majority of Republicans. These petty and vindictive measures gave hardcore conservatives the whip hand in drafting legislation and marginalized GOP moderates committed to bipartisanship. And they radicalized Democrats, who, utterly frozen out of the legislative process, had no incentives to seek common ground with the majority on anything.

Pay to play. Former Majority Leader Tom DeLay (R-Texas) was the mastermind of the GOP's "total war" approach to congressional politics. His K Street project sought a GOP monopoly on corporate campaign contributions, setting up a "pay to play" relationship between special interests and lawmakers. Tireless in the pursuit of power, the Hammer's extracurricular activity included engineering Texas' 2003 "re-redistricting," which gave Republicans five new seats in the 2004 election.

The DeLay Republicans also sought to consolidate their hold on power by spending taxpayers' money with abandon. From 2000 to 2005, federal spending ballooned by 25 percent. And while U.S. troops in Iraq scrounged for body armor and steel to fortify their soft-skinned vehicles against roadside bombs, the GOP majority lavished billions on pork barrel projects through an explosion of "earmarks," whose cost rose from $17.7 billion in 2000 to $29 billion in 2006.

Addicted to spending, chummy with special interests, pathologically partisan -- the Republican Congress by 2006 bore little resemblance to Newt Gingrich's band of budget-balancing, small-government "revolutionaries" who seized control of Congress in 1994. Richard Viguerie, a veteran conservative activist, offered this withering assessment of the DeLay Republicans: "When Tom and his bunch first ran, they campaigned against the cesspool in Washington. After a while they looked around and said, 'Hey, this isn't a cesspool, it's a hot tub.'"

Democrats must move swiftly to restore public trust in Congress. This means shutting down the GOP's grand barbecue, banning lobbyists from legislative drafting sessions, restoring fiscal discipline, and reforming a federal tax code that the Republicans turned into an instrument for political redistribution of wealth up the income scale. It also means replacing the toothless House and Senate ethics committees with an investigatory body that has the power to bring criminal charges, and adopting more radical reforms, like public financing of congressional elections.

Out of respect for the workings of parliamentary democracy, the new majority ought to restore reasonable partisan ratios to committees and respect the rights of the GOP minority. One key lesson from the last six years of unalloyed GOP dominance in Washington is that seeking bipartisan compromise isn't just a matter of civility or comity, it's often a matter of better policy. The majority isn't always right. Considering a wider range of views and reconciling divergent interests isn't a sign of political weakness or feeble conviction; it can be a way to fashion more intelligent, fair, and enduring legislation that can win broad public backing.

The GOP's downfall illustrates a timeless truth about U.S. politics: You can get away with divorcing politics from governing for a while, but sooner or later people figure out you aren't interested in solving their problems.

Ideological stability. Today's politics of polarization is something new and reflects the "Europeanization" of our politics. Historically, U.S. parties have been heterogeneous coalitions. FDR's New Deal majority, for example, combined Northern ethnics and liberals, Western progressives and Bourbon Democrats of the segregated South. In recent years, however, U.S. parties have gravitated toward their ideological extremes, as conservatives have quit the Democratic Party and Republican liberals have become an endangered species. This "great sorting out," as William A. Galston of The Brookings Institution has called it, has made America's polyglot parties more like Europe's ideologically cohesive parties.

But as the midterm election showed, the parties are far more polarized than the electorate. Americans didn't move to the right in this decade, just as they didn't move left during the Clinton years; in fact, they've hardly moved at all over the past 30 years. During that time, notes Galston, about one-fifth of voters have described themselves as liberal, one-third as conservative, and the rest, a plurality of about 45 percent, as moderates. In the absence of calamities like the Great Depression, Americans just aren't very susceptible to ideological mood swings.

This ideological stability is equally bad news for polarizers of the left. Since the 2004 election, wealthy liberals, lefty bloggers, and interest groups have been demanding that Democrats reciprocate their opponents' belligerent partisanship. Only by standing up for core liberal convictions, they argue, can Democrats galvanize a new progressive majority and "take America back." It sounds stirring, but there are three problems with that theory. First, most 2006 voters expressed a strong preference for cooperation over partisan confrontation between Bush and the Democratic Congress. Second, in moderate America, there simply aren't enough liberals to get Democrats anywhere near a majority. Third, liberal and centrist Democrats sometimes interpret their party's core principles differently, especially on such important issues as the use of force, the benefits of trade, the role of government, and questions about religion and morality.

It takes consummate political skill to manage these tensions within the Democratic coalition. President Clinton did so with policy innovations that synthesized liberal and centrist insights in fresh ways -- and that worked in real life. Perhaps today's liberals can replicate Clinton's achievement with new ideas that tilt more to the left. But this much is certain: Sustaining and managing a broad, center-left coalition, not ideological purism, is the Democrats' key to success.

The Democrats' immediate challenge is to consolidate their tenuous hold on the center and sustain the momentum of the 2006 victory into the 2008 presidential election cycle. The party's new House majority prefigures a possible national Democratic majority. It was achieved by the addition of mostly moderate Democrats, many from red states, who won in competitive and even GOP-leaning districts. To recapture the White House in 2008, the party's nominee likely will have to turn several red states blue by rolling up hefty margins among moderates and independents.

But where Democrats in 2006 could rely on the Republicans' abject failure as a governing party to deliver victory, they must now advance their own positive ideas for confronting the nation's most pressing problems. The 2008 election will be about ideas, not partisan enmity or ideology.

Will Marshall is president of the Progressive Policy Institute.