How much difference could one man possibly make to Kamala Harris’s presidential campaign? A great deal, possibly — but not if you’re talking about Tim Walz, the unholy love child of Bernie Sanders and Garrison Keillor who was picked on Tuesday as the would-be veep by the current veep.

No, I’m talking about Jerome Powell. 

You may have noticed some turbulence in the stock markets this week, and you may have heard a story — an untrue story — that this is a response to a weak employment report.

The jobs numbers weren’t great, but they’re fine.

The past week’s topsy-turvy markets were convulsed largely by exoteric stuff of little relevance to ordinary investors, specifically an interest-rate hike at the Bank of Japan that messed up the “yen carry trade” — an investment strategy based on exploiting differences between interest rates in different countries. 

That’s what drove the downturn in the market, which was largely reversed in the days after.

But Democrats are telling a different story, hoping to influence Powell and his Federal Reserve colleagues.

The Fed is independent — but, then, so is the Supreme Court, in theory, and that hasn’t stopped Democrats from trying to apply political pressure to get the outcomes they demand by any means necessary.

Democrats are desperate for the Fed to cut interest rates and give the economy a little bit of a sugar rush before the November elections.

Rates have been painfully high for what seems like forever (but in reality only a few years) as the Fed has done its best (and it is one of the few big institutions in American public life that really does seem to try to do its job) to wring all that awful Joe Biden-era inflation out of the economy.

That has made life miserable for people who want to borrow money to buy houses or cars, for a lot of the people who sell houses and cars, and for many other Americans, especially those of modest or middle-class means.

A rate cut could goose some economic activity — and it also could reignite inflationary pressures. Democrats are ready to order the vodka shots now and worry about the hangover in January. 

Over at The New York Times, poor Paul Krugman is practically kicking his cat and waving his Nobel Prize around while shouting about our “pre-recessionary” economy. GDP grew at 2.8% last quarter, twice the rate of the previous quarter, which is pretty decent.

And some of you will remember that not long ago when we had two consecutive quarters of GDP contraction — one of the textbook red flags for a recession — Prof. Krugman was among those denouncing all talk of recession as the work of partisans and ignoramuses.

That our most famous economist’s analysis just might be tinged with wishful partisan thinking is suggested by the frank headline of his column from the summer of 2022: “I Was Wrong about Inflation.” 

Now Prof. Krugman is once again high on certitude: “It’s already clear that the Fed made a mistake by not cutting rates last week; indeed, it probably should have begun cutting months ago,” he writes, adding that the Fed “can and should make a substantial cut — probably half a percentage point, rather than its usual quarter-point — at its next meeting, scheduled for mid-September.” Prof. Krugman acknowledges that a rate cut would help Democrats but insists that the case for his policy is “overwhelming.”  

That’s an interesting tightrope for Democrats to walk: On one hand, they want to argue that the economy has done wondrously under the management of President Biden and his No. 2.; on the other hand, they know that isn’t true, that the economy’s performance has been mediocre for many and quite bad for some, and that the right kind of signal from the Fed in September would help Democrats get economic credit rather than blame. (My usual caveat: The effect of the president on the economy is wildly exaggerated in our political discourse.)

And so the specter of “pre-recession” rises from the swamp of the New York Times editorial page and similar sources. 

Harris’s choice of big-spending progressive Tim Walz as her running-mate suggests that she means to run an old-fashioned guns-and-butter-and-lots-more-butter campaign, promising voters — especially members of public-sector unions — all the ice-cream they can eat and all the ponies they can ride, the gob-smacking cost of which will be someone else’s problem in a few years.

That is, of course, a big part of how we got into the current economic mess: by overextending COVID-era stimulus measures and shunting rivers of money into an economy still constrained by supply-chain problems, with the predictable result of high inflation. 

If the Fed doesn’t give Democrats what they want, look for them to trash it — the same way they have been trashing the Supreme Court since it stopped acting as a Pez dispenser for progressive social policies.

Jerome Powell, who has served with Democrats as well as Republicans, is one of the last men in Washington who seems committed to actually doing his job. 

There’s no political future in that, God knows, but sometimes virtue really had better be its own reward.