Lord knows we’ve pulped as many pine trees as anyone else encouraging Mayor Bloomberg to throw his hat into the ring for president, but he’s just come through the kind of patch that makes us wonder why. We could put up with his bellyaching about the National Rifle Association, wrong as he might be; we could lay aside his obsession with public health; we could shrug when he takes a powder in the fight over Columbia University’s insistence on giving a forum to President Ahmadinejad (the mayor seemed testy and annoyed that everyone was making such a fuss). But when the mayor gets up on a Tory soapbox in Blackpool, England, and denounces the fiscal principles of the very political party that he used as a stepping stone to public office as “lunacy,” he loses us.

Our Jill Gardiner had a report of the mayor’s demarche on page one of Monday’s Sun. The mayor didn’t denounce the GOP by name, but he derided fiscal conservatives in America and how “too many of them want to run up enormous deficits.” Quoth the mayor: “That’s not conservatism — that’s alchemy, or, if you like, lunacy.” He happened to be standing in the midst of the Tory Party conference in the very country from which King George oppressed American colonies, including New York, with onerous taxation. The conservatives he mocked are the ones who mounted a fiscal revolution to carry on the fight against excessive taxation. And whatever success Mr. Bloomberg has had as a politician is owed in large-, though not exclusive-, measure to the tax-cutting that President Bush pushed through and that has kept this city and country growing at an astonishing pace.

And, to top it off, this is bringing down the ratio of the deficit to GDP to numbers undreamed of by Mr. Bush’s critics. We’ve been beating this drum for months in two editorials about the “incredible shrinking deficit” and one, about Mr. Bush’s September 20th press conference where the president declared, “I’m a Supply-Sider.” The fact is that budget deficits have been plunging as the Bush tax cuts kicked in — $413 billion in 2004, dropping to $318 billion in 2005, dropping to $248 billion in 2006, and dropping to a projected $158 billion in 2007. The deficit as a percentage of GDP will plunge this year to a scant 1.2%, a third of what it was in 2004. “We did it by cutting taxes,” the president said. “The tax cuts worked.”

Somehow Mr. Bloomberg forgot about all this when he strutted onto King George III’s platform and started denouncing the political party that gave him his start. It’s a tragedy. The mayor has so many admirable qualities. Yet he’s been running around griping about how a short, Jewish man who’s for gay marriage and against guns and cigarettes can’t win the presidency. We don’t think the mayor’s social liberalism is insurmountable. This country has had a number of presidents who are socially liberal. What would be insurmountable is a campaign based on mocking the tax cuts that were gained by the conservatives.

If that’s what he wants to do, he can hang up his spurs and go straight to philanthropy. It’s certainly not a recipe for political success, as the failures of deficit-hawk presidential candidates from Ross Perot to Paul Tsongas can attest. And we’d like to think the mayor knows better. In Britain, he did talk of our international competition and of how “one of the things I want to talk about when I get back is, at the very same time we’re in our country walking away from free trade and walking away from immigrants, these other countries are trying to make themselves more of a destination, make themselves more welcoming.” We’d like to see him aim to be less of a scold and more of voice for the free trade, limited government, pro-immigration, pro-growth, open economy, unafraid-of-change world view that friends in both parties call sanity.