The Republican candidates for president have some major differences in their policies and their personal lives. But they have one striking thing in common - they all say the federal government is responsible for the financial crisis. Even Newt Gingrich (pilloried for having been a Freddie Mac lobbyist)says: The fix was put in by the federal government.

The notion that the federal government, via the Community Reinvestment Act (CRA) and by pushing housing finance giants Fannie Mae and Freddie Mac to meet affordable housing goals, was responsible for the financial crisis has become Republican orthodoxy. This contention got a boost from a recent lawsuit the Securities and Exchange Commission (SEC) filed against six former executives at Fannie and Freddie, including two former CEOs. Today's announcement by the SEC proves what I have been saying all along - Fannie Mae and Freddie Mac played a leading role in the 2008 financial collapse that wreaked havoc on the U.S. economy, said Congressman Scott Garrett, the New Jersey Republican who is chairman of the financial services subcommittee on capital markets and government-sponsored enterprises (GSEs).

But the SEC's case doesn't prove anything of the sort, and in fact, the theory that the GSEs are to blame for the crisis has been thoroughly discredited, again and again. The roots of this canard lie in an opposition - one that festered over decades - to the growing power of Fannie Mae, in particular, and its smaller sibling, Freddie Mac. This stance was both right and brave, and was mostly taken by a few Republicans and free-market economists - although even President Clinton's Treasury Department took on Fannie and Freddie in the late 1990s. The funny thing, though, is that the complaint back then wasn't that Fannie and Freddie were making housing too affordable. It was that their government-subsidized profits were accruing to private shareholders (correct), that they had far too much leverage (correct), that they posed a risk to taxpayers (correct), and what they did to make housing affordable didn't justify the massive benefits they got from the government (also correct!). Indeed, in a 2004 book that recommended privatizing Fannie and Freddie, one of its authors, Peter Wallison, wrote, Study after study has shown that Fannie Mae and Freddie Mac, despite full-throated claims about trillion-dollar commitments and the like, have failed to lead the private market in assisting the development and financing of affordable housing.

When the bubble burst in the fall of 2008, Republicans immediately pinned the blame on Fannie and Freddie. John McCain, then running for president, called the companies the match that started this forest fire. This narrative picked up momentum when Wallison joined forces with Ed Pinto, Fannie's chief credit officer until the late 1980s. According to Pinto's research, at the time the market cratered, 27 million loans - half of all U.S. mortgages - were subprime. Of these, Pinto calculated that over 70 percent were touched by Fannie and Freddie - which took on that risk in order to satisfy their government-imposed affordable housing goals - or by some other government agency, or had been made by a large bank that was subject to the CRA. Thus it is clear where the demand for these deficient mortgages came from, Wallison wrote in a recent op-ed in The Wall Street Journal, which has enthusiastically pushed this point of view in its editorial section since the crisis erupted.

But Pinto's numbers don't hold up. The Financial Crisis Inquiry Commission(FCIC) - Wallison was one of its 10 commissioners - met with Pinto and analyzed his numbers, and concluded that while Fannie and Freddie played a role in the crisis and were deeply problematic institutions, they were not a primary cause. (Wallison issued a dissent.) The FCIC argued that Pinto overstated the number of risky loans, and as David Min, the associate director for financial markets policy at the Center for American Progress, has noted, Pinto's number is far bigger than that of others - the nonpartisan Government Accountability Office estimated that from 2000 to 2007, there were only 14.5 million total nonprime loans originated; by the end of 2009, there were just 4.59 million such loans outstanding.

The disparity stems from the fact that Pinto defines risky loans far more broadly than most experts do. Min points out that the delinquency rates on what Pinto calls subprime are actually closer to prime loans than to real subprime loans. For instance, Pinto assumes that all loans made to people with credit scores below 660 were risky. But Fannie- and Freddie-backed loans in this category performed far better than the loans securitized by Wall Street. Data compiled by the FCIC for a subset of borrowers with scores below 660 shows that by the end of 2008, 6.2 percent of those GSE mortgages were seriously delinquent, versus 28.3 percent of non-GSE securitized mortgages.

To recap: If private-sector loans performed far worse than loans touched by the government, how could the GSEs have led the race to the bottom?

Another problematic aspect to Pinto's research is that he assumes the GSEs guaranteed risky loans solely to satisfy affordable housing goals. But many of the guaranteed loans didn't qualify for affordable housing credits. The GSEs did all this business because they were losing market share to Wall Street - their share went from 57 percent in 2003 to 37 percent by 2006. As the housing bubble grew larger, they wanted to recapture their share and boost their profits.

Indeed, the SEC lawsuit specifically says Fannie and Freddie began to do more risky business not to meet their goals, but rather to recapture market share - and they began to do so aggressively in 2006, when the market was already peaking. So while the GSEs played a huge role in blowing the bubble bigger than it otherwise would have been - and the numbers in the SEC complaint are huge - they followed, rather than led, the private market.

It's also very hard to look at what happened in the crisis and conclude that nothing went wrong in the private sector. Note that the other Republican members of the FCIC refused to sign on to Wallison's dissent. Instead, they issued their own dissent. Single-source explanations, they said, were too simplistic.

Yet despite all that, the one-note Republican refrain hasn't changed. The explanation is obvious: The government sucks rant polls well with conservatives. Mix in an urge to counter the equally simplistic story from the left - that the crisis was entirely the fault of greedy, unscrupulous bankers - and you get a strong resistance to the facts. Maybe there's a deeper reason, too. For many, belief in the all-knowing market was (and is) almost a religion. This financial crisis challenged that faith by showing the market would indeed allow loans to be made that could never be paid back, and by showing that highly paid financial services executives aren't gods, and that many of them are stupid and venal and all too human.

So maybe the Republican orthodoxy is understandable, but that doesn't mean it isn't scary. Of course, there's the great line from Edmund Burke: Those who do not know history are destined to repeat it. Our housing market is a mess that threatens to drag down the entire economy, and whoever is president in 2013 needs to have a plan. Denying the facts is not a good start.

(Bethany McLean is a Reuters columnist, contributing editor at Vanity Fair, and co-author with Joe Nocera of All the Devils are Here: The Hidden History of the Financial Crisis. Any opinions are her own.)