“Now Gov. Romney believes that with even bigger tax cuts for the wealthy, and fewer regulations on Wall Street, all of us will prosper. In other words, he’d double down on the same trickle-down policies that led to the crisis in the first place.” — President Obama in an ad released Sept. 27.

This is Obama’s core message. In one way or another, he says it all the time. It’s his kicker on the stump. You cannot watch an interview with the President or one of his subalterns without hearing it.

And yet, I don’t think I’ve ever heard a TV interviewer, host or pundit ask, “What are you talking about?”

Finally, the Washington Post’s “fact-checker,” Glenn Kessler, (not exactly a darling of the political right) tackled it recently. He found that it’s a lie, giving it three “Pinocchios” out of four. He also found that the Obama campaign has virtually no citations to back up the claim. The supporting material for the ad quoted above cites a single column by the Post’s liberal blogger, Ezra Klein, who told Kessler: “I am absolutely not saying the Bush tax cuts led to the financial crisis. To my knowledge, there’s no evidence of that.”

Klein is right. So is Kessler. “It is time for the Obama campaign to retire this talking point,” Kessler concluded, “no matter how much it seems to resonate with voters.” He would have given it the full four Pinocchios save for the fact that Obama occasionally throws in “deregulation” along with “tax cuts” as part of the explanation. In its defense, the Obama camp says it means all of Bush’s policies, not just the tax cuts it harps on almost exclusively — never mind that even Obama admits Bush issued more regulations than he did.

The question of what caused the crisis is obviously still controversial (though, Kessler notes, the official inquiry makes no mention of Bush’s tax cuts). But a consensus seems to be forming around the following narrative: The federal government, out of an abundance of concern for the plight of the poor and middle class, made it too easy to buy a home. Congress, on a bipartisan basis, set unrealistic affordable-housing goals for Fannie Mae and Freddie Mac. President Clinton used those goals to expand access to mortgages to low-income borrowers. Then President George W. Bush, with the approval of Congress, expanded the practice, until way too many low-income or otherwise underqualified Americans owned mortgages they couldn’t afford.

A mixture of greed, idealism, cynicism and stupidity led to the practice of bundling those iffy mortgages into financial instruments that Wall Street didn’t know how to handle and regulators didn’t know how to regulate. As Rep. Barney Frank, D-Mass., put it in 2003, he wanted to “to roll the dice a bit” on regulating subprime mortgages.

When the Washington-abetted housing boom went bust, regulators demanded immediate markdowns of mortgage-backed securities, which required financial institutions to sell them, creating a fire-sale atmosphere that fueled the panic even more. The Federal Reserve responded by letting money tighten in a way it hadn’t since the 1930s.

Some Obama defenders will say that Bush’s deficits made it harder to deal with the crisis. That seems reasonable, even if it’s a red herring in the debate about what caused the crisis. And Obama’s record on deficits hardly gives him much standing.

I once thought that Obama’s relentless Bush-blaming was simply a mix of political expediency and gracelessness. But the truth is more complicated. Liberals have smartly, albeit cynically, laid the case that Bush was Herbert Hoover in order to make the claim that Obama is Franklin D. Roosevelt. For this to work, Hoover must be remembered as a do-nothing free-market guy. But Hoover was no such thing. He nearly tripled government spending in response to the Depression. FDR used Hoover’s spending as a baseline for his own, even as he dishonestly decried Hoover’s passivity.

Obama has done largely the same thing. The first bailouts of the crisis were supported by Obama but launched by Bush. The same goes for the first stimulus. Obama simply tripled down on all that while claiming he was breaking with Bush.

Or maybe I have that all wrong. Maybe we could get some clarity by asking the President, “What are you talking about?”

Jonah Goldberg is the author of the new book “The Tyranny of Clichés.” You can write to by e-mail at JonahsColumn@aol.com, or via Twitter @JonahNRO.