In 2006 and 2008, voters inflicted on Republicans the worst back-to-back electoral drubbing any party has received since the Great Depression, when Franklin Delano Roosevelt all but destroyed the Party of Hoover. Republicans quickly reached a consensus about why they lost so badly: They had failed to be sufficiently Republican.

This consensus still moves the party -- and since it is false, it moves them to make mistakes.

“We lost our way” was the cliche that expressed the Republican theory. “I believe we did not just lose our majority, we lost our way,” said Congressman Mike Pence, of Indiana, as he ran to replace the House Republican leadership after the 2006 elections. “In recent years, our majority voted to expand the federal government’s role in education by nearly 100 percent, created the largest new entitlement in 40 years, and pursued spending policies that created record deficits, national debt and rampant earmark spending.”

So widespread did this view become that the Republican leadership itself embraced it. Eric Cantor, Paul Ryan and Kevin McCarthy -- high-ranking House Republicans all -- wrote in a 2009 op-ed, “By the fall of 2006, it had become abundantly clear that Republicans had severely lost our way.” Among other mistakes, “we had significantly increased federal spending.” Speaker John Boehner has said the same thing: “Republicans lost our way on fiscal responsibility.”

Expunging Impurity

For decades, conservatives have been trying to pull the Republican Party rightward and root out first liberals and then moderates. But that impulse grew stronger in the aftermath of the political defeats in the late years of George W. Bush’s administration, because conservatives believed that ideological impurity, especially on spending, had caused those losses.

The history of modern conservatism reinforced this view. In the late 1970s, Republicans recovered from their post-Watergate lows by turning to the right in the person of Ronald Reagan. A similar rebound happened in the early 1990s. Throughout those years, the Republican Party grew by attracting voters who were ancestral Democrats but opposed to tax increases, abortion or affirmative action. Republicans believe that their 2010 election victories were rewards for returning to the true path of conservatism that they had left in the Bush years.

There are elements of truth in the conservative story. Bush-era Republicans did spend too much, refusing to make room for increased security budgets by cutting anything else. Bush’s sincere belief that K-12 education could be reformed from Washington was naive. The Republicans’ almost uniform rejection of President Barack Obama’s stimulus and health-care legislation really did contribute to their victories in 2010.

Misreading History

But there’s little evidence that big government was the reason, or even an important reason, for Republican defeats at the end of the Bush years. Take the top item on the list of conservative charges against Bush, his expansion of Medicare to cover prescription drugs. That idea was overwhelmingly popular, including among self-described conservatives whom pollsters contacted. It’s hard to believe that Bush would have won Florida in 2000 without promising to match the Democrats on the issue, or that he would have won Ohio in 2004 without having made good on the promise. He won both states by small margins, and through them the Electoral College.

Republicans were more popular in Bush’s first term, when they were expanding entitlements, than in his second term, when they were trying to reform one (Social Security). For most of the second term, they exercised more spending restraint than they had done in the first term -- and again, there was no evidence it helped them politically.

Losing Independents

If Republican overspending drove voters away, they should have lost support first among conservatives. But there was no sign of a demoralized base in 2006. Exit polls found that self-identified Republicans made up a healthy 36 percent of the electorate that year, and they voted for the party’s candidates by roughly the same huge margin they had voted for them in the banner Republican year of 2004. It was among independent voters that Republicans got slaughtered. (House Republicans lost independents by three points in 2004, but 18 points in 2006.)

It seems much more likely that Republicans lost in 2006 because of the bleeding in Iraq, corruption in Washington, wage stagnation and the lack of any agenda by the party to do anything about these or other problems. Some of these issues had faded in importance by 2008, but in that year voters were also ready for a change after eight years of Republican control of the White House and, above all, dismayed by the economic crisis. In 2008, 60 percent of voters said the Republican presidential candidate, John McCain, wasn’t “in touch with people like them” -- and 79 percent of people who felt that way voted against him. That’s what defeated Republicans, not a perception that they were doctrinally impure.

Creating a Mythology

This isn’t ancient history. The view that Republicans must avoid accommodation at all costs -- that the principal obstacle to achieving conservative policy goals is a lack of spine and not, say, a lack of popular support -- made them lose at least two Senate races in 2010. In Colorado and Nevada, conservative primary voters rejected two electable, conventionally conservative candidates because they were considered part of a compromising establishment. If Republicans fall two votes short of repealing Obama’s health-care plan in 2013, the mythology they have created will be part of the reason why.

That mythology influences the Republican presidential primaries, too. It’s why they have, to an unusual extent, showcased unpopular ideas that have no chance of going anywhere, such as abolishing the Environmental Protection Agency. It is part of the reason for the resistance to former Massachusetts Governor Mitt Romney: Conservatives fear he would be a big-government Republican, like Bush, and lead the party again to ruin.

Meanwhile, the real mistakes of the Bush years keep being made. Republicans had nothing to say about wage stagnation then and are saying nothing about it now. The real cost of Republicans’ fixation on ideological purity is that it distracts them from their real problems, and the nation’s.

(Ramesh Ponnuru is a Bloomberg View columnist and a senior editor at National Review. The opinions expressed are his own.)

To contact the writer of this article: Ramesh Ponnuru at rponnuru@bloomberg.net

To contact the editor responsible for this article: Timothy Lavin at tlavin1@bloomberg.net