Remember when, after the 2008 financial meltdown, both parties really wanted to end “too big to fail” — it’s just that they couldn’t agree on how to do it? It turns out that neither party really wants this — at least not if that principle interferes with business as usual.

Sen. Chuck Schumer (D-NY) is leading the bipartisan charge to allow banks to take risks they shouldn’t be taking again.

Two years after the 2008 financial crisis, President Obama enacted the Dodd-Frank financial-regulation law to stop such a thing from happening ever again. But the law wasn’t enough, Obama said at the bill-signing. “Regulators will have to be vigilant,” he said, and not be fearful of “powerful interest groups.”

It turns out one of those powerful interest groups determined to block change is . . . Congress.

Since the law passed, the Federal Reserve and other regulators have been trying to get the banks to reduce risky lending. One proposed Fed rule would force banks to hold enough “easy-to-sell” investments so that in a crisis, they could sell them to raise enough money to support themselves for 30 days, without having to turn to the government for help.

What are easy-to-sell investments?

Treasury bonds are pretty safe, because you can pretty much always buy and sell them, even in a credit crunch. (Though there are exceptions to every rule, people usually want to buy, not sell, these bonds in a crisis, as they flee riskier investments like stocks.)

Fannie Mae and Freddie Mac bonds are safe, because the government guarantees them (it shouldn’t, but it does).

So regulators said two years ago that they’d count these bonds toward the 30-day rule — but nothing else. Politicians, however, want banks to be able to hold another type of investment: municipal bonds.

Labeling muni bonds as “easy to sell,” you see, increases demand. And that makes it cheaper for cities and states to borrow — something that grows ever more important as they strain to provide public services under impossible-to-meet pension and health-care promises to their union workforces.

Give the regulators credit: Though Schumer and House Republicans have been bugging them for two years to change this rule before it takes effect, the experts haven’t budged. And for good reason: municipal bonds are not easy to sell.

Consider: Muni bonds are a $3 trillion market — compared to a $20.7 trillion market for Treasury securities and Fannie and Freddie. Every day, traders buy or sell $684.5 billion in Treasury or Fan/Fred bonds. They trade only $8.6 billion in municipal bonds.

It’s harder to sell a muni bond because muni bonds are tax-exempt — but only in the state that issued them. So the bonds don’t enjoy nationwide demand. Treasury bonds, by contrast, enjoy global demand.

Plus, those who buy muni bonds tend to want to keep them for a long time. They’re interested in interest income, not making a quick profit. People buy Treasury bonds, by contrast, for a short time, often until they can think of something else they want to buy.

In the bad times, though, it might be even harder to sell a muni bond.

Think about Puerto Rico’s bonds: They’ve lost value as the island has defaulted on some investments. What if, a few years down the line, people worry about Illinois and New Jersey bonds in the same way?

What would happen is that banks wouldn’t be able to raise their needed 30-day cash. And Washington would have to offer a bailout. After all, it’s the feds who told everyone that these bonds were just as safe as Treasury bonds in the first place, right?

The Republican House has passed a bill forcing regulators to change their minds, The Wall Street Journal reported last week. Schumer is trying to get the Senate to do the same.

When the next bailout comes, don’t blame regulators. Blame the establishment pols who don’t want a safer financial system — because it means a bigger headache for them now.

Nicole Gelinas is a contributing editor to the Manhattan Institute’s City Journal.