On the campaign trail, McCain, the Republican presidential nominee, struck a populist tone. Speaking in Florida, he said that the economy’s underlying fundamentals remained strong but were being threatened “because of the greed by some based in Wall Street and we have got to fix it.”

But his record on the issue, and the views of those he has always cited as his most influential advisers, suggest that he has never departed in any major way from his party’s embrace of deregulation and relying more on market forces than on the government to exert discipline.

While McCain has cited the need for additional oversight when it comes to specific situations, like the mortgage problems behind the current shocks on Wall Street, he has consistently characterized himself as fundamentally a deregulator and he has no history prior to the presidential campaign of advocating steps to tighten standards on investment firms.

He has often taken his lead on financial issues from two outspoken advocates of free market approaches, former Senator Phil Gramm and Alan Greenspan, the former Federal Reserve chairman. Individuals associated with Merrill Lynch, which sold itself to Bank of America in the market upheaval of the past weekend, have given his presidential campaign nearly $300,000, making them Mr. McCain’s largest contributor, collectively.

Obama sought to attribute the financial upheaval to lax regulation during the Bush years, and in turn to link McCain to that approach.

“I certainly don’t fault Senator McCain for these problems, but I do fault the economic philosophy he subscribes to,” Obama told several hundred people who gathered for an outdoor rally in Grand Junction, Colorado.

Obama set out his general approach to financial regulation in March, calling for regulating investment banks, mortgage brokers and hedge funds much as commercial banks are. And he would streamline the overlapping regulatory agencies and create a commission to monitor threats to the financial system and report to the White House and Congress.

On Wall Street’s Republican-friendly turf, Obama has outraised McCain. He has received $9.9 million from individuals associated with the securities and investment industry, $3 million more than McCain, according to the Center for Responsive Politics, a watchdog group. His advisers include Wall Street heavyweights, including Robert E Rubin, the former treasury secretary who is now a senior adviser at Citigroup, another firm being buffeted by the financial crisis.

If many voters are fuzzy on the events that over the weekend forced Lehman Brothers Holdings Inc. into bankruptcy and Merrill Lynch & Company to be swallowed by the Bank of America Corporation, the continuing chaos among the most venerable names in American finance -- coming on top of the recent government seizure of mortgage giants Fannie Mae and Freddie Mac and the demise of the Bear Stearns Companies -- has stoked their anxiety for the economy, the foremost issue on voters’ minds.

So it was that first Obama and then McCain rushed out their statements before most Americans had reached their workplaces.