WASHINGTON — Put it in the history books: The country was officially diagnosed with a job-killing recession Monday, and woeful new evidence showed it's getting worse. Wall Street convulsed at the news, tanking 680 points, and Washington pledged even more help to try to ease the pain.

With the economic pain likely to stretch well into 2009, Federal Reserve Chairman Ben Bernanke said Monday he stands ready to lower interest rates yet again and to explore other rescue or revival measures.

Rushing in reinforcements, Treasury Secretary Henry Paulson, who along with Bernanke has been leading the government's efforts to stem the worst financial crisis since the 1930s, pledged to take all the steps he can in the waning days of the Bush administration to provide relief. Specifically, Paulson is eyeing more ways to tap into a $700 billion financial bailout pool.

On Capitol Hill, House Speaker Nancy Pelosi, D-Calif., vowed to have a massive economic stimulus package ready on Inauguration Day for President-elect Barack Obama's signature.

That measure — which could total a whopping $500 billion — would bankroll big public works projects to generate jobs, provide aid to states to help with Medicaid costs and provide money toward renewable energy development. Crafting such a colossal recovery package would mark a Herculean feat: Congress convenes Jan. 6, giving lawmakers just two weeks to complete their work if it is to be signed on Jan. 20.

President George W. Bush, in an interview with ABC's "World News," expressed remorse about lost jobs, cracked nest eggs and other damage wrought by the financial crisis. "I'm sorry it's happening, of course," Bush said. The president said he'd back more government intervention.

None of the pledges for more action could comfort Wall Street investors. The Dow Jones industrials plunged 679.95 points, or 7.70 percent, to close at 8,149.09.

It was another white-knuckle day, punctuated by grim economic reports. An index of manufacturing activity sank to a reading of 36.2 in November, a 26-year low, the Institute for Supply Management reported. Construction spending fell by a larger than expected 1.2 percent in October, the Commerce Department said.

Adding to the gloom, the National Bureau of Economic Research, a group of academic economists, concluded Monday that the country has been suffering through a recession since December 2007.

With NBER's decision, the United States has fallen into two recessions during Bush's eight years in office. The first one lasted from March 2001 to November of that year.

The economy jolted into reverse in the final three months of last year. After a short spring rebound, it contracted again in the summer. Economists say it is still shrinking and will continue to do so through at least the first quarter of next year.