We told you last month about the role of the credit ratings agencies in helping to cause the financial crisis. A major part of the problem, in a nutshell, is that the major ratings agencies -- Moody's, Standard & Poor's, and Fitch -- are paid by the institutions (often investment banks) who are issuing the bonds. That gives the agencies a clear incentive to produce favorable ratings, or risk seeing the banks hire a different ratings agency that's willing to offer a better rating.

But over the weekend, in a profile of Sen. Chuck Schumer, the New York Times revealed that the veteran New York Democratic lawmaker -- who, with seats on both the finance and banking committees, has built a reputation as a key ally of the financial sector, a major industry in his home state -- played a major role in stymieing efforts to fix that problem.

Here's what happened:

In 2006, Christopher Cox, the Bush-appointed chair of the Securities and Exchange Commission -- and hardly a left-wing proponent of heavy-handed government regulation -- became convinced that the conflict of interest problem needed to be addressed.

A plan to give the SEC more regulatory authority "drew broad, bipartisan support," says the Times. But it was opposed, of course, by the ratings agencies themselves ... who turned to Schumer.

"They knew Schumer would support them," one former Moody's executive told the Times. "He was their go-to guy."

The paper adds: "While the Manhattan-based agencies were not significant campaign donors to Mr. Schumer or the Senate campaign committee, their lobbyists and many of their clients were."

As an alternative to Cox's plan, Schumer advocated a largely voluntary approach in which regulators would simply encourage the agencies to disclose their ratings methods. "They're making good-faith efforts," Schumer told Cox at a 2006 Senate hearing.

Ultimately, says the Times, Schumer was able to get the measure amended "so that it explicitly prohibited the S.E.C. from regulating the procedures and methods the agencies use to determine ratings."

In other words, he appears to have blocked the crucial part of the legislation. Sean Egan, of Egan-Jones Ratings -- one of the few agencies that largely avoided buying into the mortgage bubble, perhaps in part because it's structured to avoid conflicts of interest -- told the Times: "The bill was eviscerated. You have stripped away basic safeguards for the investors."

And sure enough, under the weak regulatory system that Schumer had helped to ensure, the agencies,as we've seen, offered high ratings to bonds based on risky sub-prime loans, encouraging investors to see them as secure, and ultimately helping to inflate the mortgage bubble.

Schumer claims to have learned from his mistakes. He supported a belated but necessary SEC move earlier this month to meaningfully address the conflict of interest problem, and related issues, saying: "The work at these ratings firms was severely compromised, and the companies were some of the biggest contributors to the current financial crisis."

But had Schumer adopted that position back in 2006, when the SEC did, the ratings agencies might not have wound up as a significant cause of our current financial turmoil.