Economic Activity Shifts Campaigns' Focus to Wall Street New developments force the campaigns to address the economy from the trail.

PUEBLO, Colo.

Sept. 15, 2008 -- Calling Monday's economic climate the most serious financial crisis since the Great Depression, Democratic presidential nominee Sen. Barack Obama attacked Sen. John McCain, R-Ariz., for supporting what Obama called a failing economic philosophy.

On Sunday, the federal government declined to bail out Wall Street investment bank Lehman Brothers, another financial institution choked by the credit crisis. The ailing firm filed for bankruptcy this morning. Another Wall Street giant, Merrill Lynch & Co, narrowly avoided suffering the same fate by offering itself to Bank of America for sale.

While addressing a crowd in his first solo rally since adding Alaska Gov. Sarah Palin to the ticket, McCain acknowledged problems caused by the nation's economic state, but claimed the economy's "fundamentals" were sound.

"There's been tremendous turmoil in our financial markets in Wall Street and it is, people are frightened by these events," he said.

"Our economy, I think, still, the fundamentals of our economy are strong, but these are very, very difficult times and I promise you we will never put America in this position again," McCain continued, in an attempt to reassure the crowd.

During a campaign event in Grand Junction, Colo., Monday afternoon, Obama said that the news about Merrill Lynch and Lehman Brothers "offers more evidence that too many folks in Washington and on Wall Street weren't minding the store."

Obama said news of the Wall Street failures reminded him of the savings and loan crisis of the 1990s, when several of those financial institutions failed and thousands of businesses and families were financially ruined in the process. Obama told voters that, if they are comfortable with the current state of the U.S. economy, they would appreciate the position of his political rival, McCain.

"I certainly don't fault Sen. John McCain for these problems," the Illinois senator said.

"But I do fault the economic philosophy he subscribes to, because it's the same philosophy we've had for the last eight years," he added.

Obama accused McCain of having a hands-off approach to the financial crisis and maintaining a philosophy that says, "Even common sense regulations are unnecessary and unwise; one that says we should just stick our heads in the sand and ignore economic problems until they spiral into crisis."

Obama then seized upon remarks McCain made in Jacksonville, Fla., that same morning, to paint his opponent as out of touch. The Republican presidential nominee admitted the difficulty caused by the nation's economic state, but claimed the economy's "fundamentals" were sound.

"Sen. McCain -- what economy are you talking about?" Obama asked the audience.

"What's more fundamental than the ability to find a job that pays the bills and can raise a family?" Obama asked, his voice rising.

"What's more fundamental than knowing that your life savings is secure, and that you can retire with dignity? What's more fundamental than knowing that you'll have a roof over your head at the end of the day?"

Running Mates Weigh In

At a "Road to Victory" rally, Republican running mate Palin delivered her standard stump speech, but also acknowledged the recent news from Wall Street.

"This is an issue of real concern," Palin told the large crowd gathered in Golden, Colo.

But, she then pointed out, "I'm glad to see the Federal Reserve has said no to using taxpayer money for a bailout."

The self-professed "Hockey Mom" also discussed her family's small business experience, saying that she had, too, experienced the stresses of the current economy.

"My family has faced the same challenges that many of you have and many across America today," she said.

"We've all built small businesses and worked hard to earn a living. We know the struggles out there," she continued.

In Michigan, Obama's running mate Sen. Joe Biden, D-Del., took the opportunity to pounce on McCain, as well.

"Ladies and gentlemen, ladies and gentlemen, I could walk from here to Lansing, and I wouldn't run into a single person who thought our economy was doing well, unless I ran into John McCain," he said.

"John McCain just doesn't seem to understand what middle-class people are going through today," Biden asserted.

At a later rally in Orlando, McCain tried to amend his earlier statement, which Obama has been mocking for months.

"Those fundamentals are being threatened today because of greed and corruption that some indulged in on Wall Street," he said.

McCain has been making similar arguments about the economy for months, earlier this summer telling radio host Laura Ingraham, "I still believe the fundamentals of our economy are strong. We've got terribly big challenges now, whether it be housing or employment or so many of the other -- health care. It's very, very tough times. It's very tough. But we're still the most innovative, the most productive, the greatest exporter, the greatest importer. Every new advancement, literally, in technology that has created this new economy throughout the world, has come from the United States economy. Do we have a lot of things to fix, do we have big challenges? Yes. But I also believe America's best days are ahead of us."

ABC News' Andy Fies, Avery Miller, and Natalie Gewargis contributed to this report.