It's a reprieve not a pardon.

Despite taking a big hit at the polls, Republicans (and the commentariat) are already starting to read their better-than-expected showing as a kind of victory. They're suggesting that Americans aren't really fed up with GOP complacency and arrogance, that the party's governing formula only needs tweaking, not rethinking. But, as history suggests, that would be the wrong lesson to take.

Consider what happened in 1966. That year, it was the Democrats who entered the midterm election in firm control of the White House, both chambers of Congress, and the Supreme Court. Liberalism dominated the political landscape then as surely as conservatism dominates today. President Lyndon Johnson and his allies in Congress had recently achieved a host of triumphs: the Civil Rights Act, Medicare and Medicaid, Food Stamps and Head Start, and the Voting Rights Act, with its principle of "one man, one vote." The liberal Warren Court was also issuing landmark decisions, including the Miranda ruling safeguarding rights of the accused, and the Griswold decision ensuring privacy rights.

Just as George W. Bush had popular support for many of his programs before running afoul of public sentiment, so too did Lyndon Johnson. Not one of the Great Society achievements listed above was ever reversed. But growing numbers of Americans did start to think that Washington was going too far. Urban crime was worsening, racial integration was roiling neighborhoods, and taxes were increasing--all feeding what was soon dubbed a "backlash" against liberalism. In the 1966 elections, Republican candidates sought to capitalize on these discontents. They stumped against "crime in the streets," denounced housing laws that they claimed would force racial integration, and stoked outrage over urban riots.

The strategy worked. In November, the GOP netted 47 seats in the House and three in the Senate. The Democrats held on to their majorities, but a signal had been sent. Only 21 of 48 pro-Johnson freshmen elected in the president's 1964 landslide survived an indication that the high tide of liberalism was receding. House Minority Leader Gerald R. Ford (R-Mich.) taunted the president: "It's going to be rough going for him around here," he said. "Congress will write the laws, not the executive branch." It's a sentiment--part bluster, part recognition of the rebuke sent to the president--that you could imagine Sen. Harry Reid (D-Nev.) or Rep. Nancy Pelosi (D-Calif.) articulating soon.

Around the country, other signs of voter misgivings with liberal dominance were emerging. In California, a politically untested former movie star turned the riots in Watts and the mayhem at the University of California into an indictment of liberal leadership, ousting the incumbent Pat Brown to become governor. Ronald Reagan would lead the fledgling conservative movement for another two decades. Republicans then buzzed with excitement at the thought of new blood filling their leadership ranks, much as Democrats today hope that a new crop of young governors and senators, from Sen. Barack Obama (D-Ill.) to Eliot Spitzer to Rep. Sherrod Brown (D-Ohio), will chart a new course for their party in the future.

Today's Republicans would do well to note how long it took Democrats to assimilate the lessons of their 1966 defeats. For the most part, they didn't attempt to tack back to the center. With some notable exceptions--such as acquiescing in a draconian crime bill in 1968--they kept promoting an expansive vision of government that included controversial planks such as busing, affirmative action, greater welfare benefits, and a focus on the root causes of crime instead of harsh punishment. In 1969, Kevin Phillips described an "emerging Republican majority." But instead of stanching the tide of defections to the GOP, Democrats allowed them to continue into the 1970s and 1980s.

Most historians look back on the 1970s, particularly George McGovern's 1972 presidential campaign, as a time when the party failed to heed signals that its policies, especially on social issues, had strayed too far from majority sentiment. The right was then able to paint liberals as out-of-touch elites who had grown arrogant with power. White Southerners, neoconservative intellectuals, and the white working-class voters later known as Reagan Democrats all drifted away from their former party as the Democrats stuck with policies and rhetoric that kept them on the losing side of rising demographic trends.

While it's simplistic to believe that history repeats itself, there are signs that the Republicans who first made strides toward political power in 1966 may now have reached their Waterloo. With the addition of John Roberts and Samuel Alito to the U.S. Supreme Court, they control all three branches of government. Like the Democrats in 1966, however, Republicans are showing telltale signs of having grown arrogant with power themselves, unable to take a hint from restless voters.

Modern conservatives' contempt for investment in cities and in environmental protection made the impact of Hurricane Katrina far worse than it had to be. Their plan to privatize Social Security--a New Deal cornerstone on which millions of Americans vitally depend hit a brick wall of popular opposition. In this wealthiest of nations, it turns out, people actually want the government to keep providing basic safeguards against economic strain, illness, and the predations of business.

Besides the public's support for social provisions, today's Republicans have underestimated the public's tolerance. Siding with religious fundamentalists, the GOP made a federal issue of Terri Schiavo's case, failing to appreciate most Americans' wish for privacy in such matters. And while gay marriage remains unpopular, on the more important question about whether to accept openly gay people in society, the Republicans hold a losing hand. Younger Americans show declining levels of anti-gay sentiment. In another generation, current conservative attitudes on homosexuality--as well as on birth control, euthanasia, and other social issues--may well seem as retrograde as overt anti-Semitism and racism seem today. If John Judis and Ruy Teixeira are right, the hard-line intolerants will be the ones caught on the wrong side of an emerging Democratic majority.

Perhaps absolute power does corrupt absolutely. The White House's abuses, such as spying on citizens and depriving suspected terrorists of basic human rights like habeas corpus, are today triggering fear outside the usual civil-libertarian circles. Bush's updating of Richard Nixon's theory--if the president does it, that means it's not illegal--isn't likely to sit well even among conservative Democrats and independents, even those who may oppose gun control or abortion.

This fall's GOP losses show serious public concern that George W Bush and the conservative movement, entrusted with great power, have violated that trust. Four decades ago, Americans sent the same hint to overreaching liberals, who then suffered for a quarter century--with declining electoral fortunes, a deteriorating public image, and ebbing power--before finally getting the message.

David Greenberg is a professor at Rutgers University and the author of Nixon's Shadow: The History of an Image.