Editor's note: Will Marshall is the president of the Progressive Policy Institute, a center-left think tank in Washington.
(CNN) -- Republicans are consoling themselves with the claim that President Barack Obama didn't win a mandate Tuesday night, even if he did renew his White House lease for another four years. They are fooling themselves, however, if they think the 2012 election merely ratified the political status quo. More than just a personal victory for Obama, the outcome was an unmistakable defeat for GOP ideology.
Disgruntled conservatives, of course, are already dressing Mitt Romney for the part of fall guy. But this is the politics of evasion. Sooner or later, GOP realists will have to reappraise the party's message rather than shoot its messenger.
That message was a call for rolling back government. Intoxicated by a potent brew of resurgent libertarian dogma and intense personal animus toward Obama, Republicans vowed to undo his major achievements: health care reform, new rules for financial markets, the regulation of carbon emissions, higher fuel economy standards for autos, and so on.
Conservatives also railed against an alleged epidemic of dependency on government; called for deep spending cuts (but no tax hikes) to reduce public deficits; threatened to roll back women's reproductive rights; and took extreme positions on tax, immigration and energy issues that seemed calculated to thwart bipartisan compromise.
Such tea party radicalism seemed to work in 2010, amid acute public dissatisfaction with the slow pace of economic recovery. But a different electorate -- larger, more moderate and more Democratic -- rejected the conservative vision this time.
In effect, the pragmatic center reasserted itself on Tuesday. According to exit polls, a plurality of voters, 41%, were moderates, and they favored Obama by 15 points. In general, voters viewed Obama as more for the middle class and Republicans as tilting toward the interests of the rich. They did not accept Romney's claims that Obama has been an incompetent economic manager; nearly half the voters instead blamed the weak economy on his predecessor.
And for all the GOP's ceaseless demonization of Obamacare, the issue seemed to work in the president's favor. Exit polls say health care registered as the voters' second most important concern (albeit a distant second to the economy and jobs). Obama won massively among these voters, which suggests that Republican promises to kill health care reform may have backfired by spurring greater intensity among its advocates.
Some Republicans point hopefully to the fact that the election barely changed the existing composition of political forces in Washington. That's true, but this was an election they could have won. With stubbornly high unemployment and the president's low approval ratings (often below the previously supposed "can't win" threshold of 50%), the Republicans had objective reality on their side. Instead, they blew it by indulging in pathological partisanship and ideological hubris.
The big question now is whether Republicans will accept the lessons of their defeat or take refuge in the usual alibis. The biggest lesson, of course, is they lost because they picked the wrong candidate -- a Massachusetts moderate who didn't given the country a clear choice between undiluted conservatism and Obama's alleged ultra-liberalism. This electoral math is no better than Romney's budget math. America may list slightly to the center-right, but no party can cede the center and win.
What Republicans really need is an analogue to the New Democrat movement of the 1990s -- a determined effort by moderates and pragmatists to reassert control over their party's agenda and electoral strategies. Whether they realize that is another matter: Democrats had to lose four out of five presidential elections between 1968 and 1992 before finally accepting that their message could no longer command electoral majorities.
Republicans don't have that luxury. Tuesday's results made it blindingly obvious that the GOP's political strategy of relying almost exclusively on white voters already has reached a dead end. As expected, white turnout was 72%, according to exit polls, two points down from 2008, and is projected to be two points lower in 2016. The GOP's bet on a kind of white identity politics -- which dates back to Ronald Reagan's successful 1966 run for governor in California and was ruthlessly perfected by Richard Nixon in 1972 -- is played out.
Meanwhile, what the National Journal's Ronald Brownstein calls the Democrats' "coalition of the ascendant" is growing by about the same amount every four years. This coalition includes minorities, young voters and women (especially single women), along with highly educated white professionals.
As they pore over election returns, expect GOP strategists to look especially ruefully at Latino voters. Obama won them by 71% to 27%, according to exit polls, improving on his 2008 performance. Assuming that Latinos would focus mainly on their economic struggles and ignore the GOP's harshly anti-immigrant stance, proved to be a major miscalculation.
A conservative governing philosophy centered on exploiting white voters' sense of cultural dispossession is a formula for political marginalization, if not demographic suicide. Any honest post-mortem of the 2012 election should lead Republican strategists to this inescapable conclusion: It's the ideology, stupid.
The opinions expressed in this commentary are solely those of Will Marshall.