While the panel, the Financial Crisis Inquiry Commission, accuses several financial institutions of greed, ineptitude, or both, some of its most grave conclusions concern government failings, with embarrassing implications for both political parties.

Many of the findings have been widely described, but its synthesis of interviews, documents and testimony, along with its government imprimatur, give it a sweep and authority that the commission hopes will shape the public consciousness. The full report is expected to be released as a 576-page book on Thursday. When the bipartisan commission was set up in May of 2009, the intent of Congress and the president was to produce a comprehensive examination of the causes of the crisis.

The report, aimed at a broad audience, was based on 19 days of hearings as well as interviews with more than 700 witnesses; the commission has pledged to release a trove of transcripts and other raw material online. The document is intended to be the definitive account of the crisis’s causes, but its authors may already have failed in achieving that aim.

Of the 10 commission members, only the 6 appointed by Democrats endorsed the final report. Three Republican members have prepared a dissent; a fourth Republican, Peter J. Wallison, a former Treasury official and White House counsel to President Ronald Reagan, has written a dissent, calling government policies to promote homeownership the primary culprit for the crisis.

The report itself finds fault with two Fed chairmen: Alan Greenspan, a skeptic of regulation who led the central bank as the housing bubble expanded, and his successor, Ben S. Bernanke, who did not foresee the crisis but then played a crucial role in the response. It criticizes Mr. Greenspan for advocating financial deregulation and cites a “pivotal failure to stem the flow of toxic mortgages” under his leadership as “the prime example” of government negligence.

It also criticizes the Bush administration’s “inconsistent response” to the crisis — allowing Lehman Brothers to go bankrupt in September 2008, for example, after earlier bailing out another bank, Bear Stearns, with help from the Fed — “added to the uncertainty and panic in the financial markets.”

Like Mr. Bernanke, Mr. Bush’s Treasury secretary, Henry M. Paulson Jr., predicted in 2007 — wrongly it turned out — that the subprime meltdown would be contained, as the report notes.

Democrats also come under fire. The 2000 decision to shield over-the-counter derivatives from regulation, made during the last year of President Bill Clinton’s term is called “a key turning point in the march toward the financial crisis.”

Timothy F. Geithner, who was president of the Federal Reserve Bank of New York during the crisis and is now President Obama’s Treasury secretary, also comes under criticism; the report finds that the New York Fed “could have clamped down” on excesses by Citigroup in the lead-up to the crisis and, just a month before Lehman’s collapse, was “still seeking information” on the vulnerabilities from Lehman’s exposure to more than 900,000 derivatives contracts.

Former and current officials named in the report, as well as financial institutions, declined on Tuesday to comment on the report before it was released , or did not respond to requests for comment.

The report will probably reignite debate over the outsize influence of Wall Street; it says that regulators “lacked the political will” to scrutinize and hold accountable the institutions they were supposed to oversee. The financial sector spent $2.7 billion on lobbying from 1999 to 2008, while individuals and committees affiliated with the industry made more than $1 billion in campaign contributions.

The report does knock down — at least partly — several early theories for the financial crisis. It says the low interest rates brought about by the Fed after the 2001 recession “created increased risks” but were not chiefly to blame. It says that Fannie Mae and Freddie Mac , the mortgage finance giants, “contributed to the crisis but were not a primary cause.” And in a finding likely to upset conservatives, it says that “aggressive homeownership goals” set by the government as part of a “philosophy of opportunity” were not major culprits.

On the other hand, the report is unsparing in its treatment of regulators. It finds that the Securities and Exchange Commission failed to require big banks to hold more capital to cushion losses and halt risky practices, and that the Fed “neglected its mission” to protect the public.

It says that the Office of the Comptroller of the Currency, which regulates national banks, and the Office of Thrift Supervision, which oversees savings-and-loans, blocked state regulators from reining in lending abuses because they were “caught up in turf wars.”

“The crisis was the result of human action and inaction, not of Mother Nature or computer models gone awry,” the report states. “The captains of finance and the public stewards of our financial system ignored warnings and failed to question, understand and manage evolving risks within a system essential to the well-being of the American public. Theirs was a big miss, not a stumble.”