GREEN BAY, Wis. — John McCain and Barack Obama clashed sharply over the economy yesterday as the two campaigns intensified their heated confrontation over who can best address the nation's volatile financial markets.

McCain provided more detail about his proposal to create a new federal regulator and assailed Obama for failing to outline his own plan. He also accused the Democratic nominee of associating with those responsible for the crisis.

"People like Senator Obama have been too busy gaming the system and haven't ever done a thing to actually challenge the system," McCain told a business group in Green Bay, pointing out that Obama had taken advice from two former executives of collapsed mortgage giant Fannie Mae.

Obama, who endorsed the rescue package announced yesterday by the Bush administration, in turn chided McCain for being hypocritical. Obama supporters pointed out that several McCain advisers have worked on behalf of Fannie, including McCain's campaign manager who defended the company against increased regulation as president of the Homeownership Alliance, an industry group.

Both candidates have received support from the beleaguered financial services industry. According to the nonpartisan Center for Responsive Politics, employees of the securities and investment field have contributed about $10 million to Obama and $7 million to McCain.

Obama has received $126,349 from employees and political action committees of Freddie Mac and Fannie Mae since 2005, more than any other member of Congress except the chairman of the Senate Banking Committee, according to the CRP. McCain has taken $21,550 from Freddie and Fannie employees.

McCain offered slightly more information about his proposal to create a new federal agency to head off future corporate collapses.

Under his plan, distressed companies could seek direct aid from a new division of the Treasury Department. The so-called Mortgage and Financial Institutions Trust would be able to issue taxpayer-funded loans or to assume responsibility for problematic assets like the mortgage-backed assets now wreaking havoc with the financial system.

The McCain campaign did not indicate how this new agency would determine which companies could receive assistance. But senior campaign aide Matt McDonald said the approach would be broadly similar to the financial rescue outlined yesterday morning by the Bush administration.

"This will get the Treasury and other financial regulatory authorities in a proactive position ... instead of reacting in a crisis mode to one situation after another," McCain said yesterday.

Obama voiced support for giving the Treasury and Federal Reserve broad powers to stabilize financial markets. And he said he fully backed efforts by Treasury Secretary Henry M. Paulson Jr. and Federal Reserve Chairman Ben Bernanke "to work in a bipartisan spirit with Congress" on an emergency plan.

"What we're looking at right now is to provide the Treasury and the Federal Reserve with as broad authority as necessary to stabilize markets and to maintain credit," he said at a somber news conference, flanked by top players in former President Clinton's economic brain trust, including former Treasury Secretary Robert E. Rubin.

Obama also advocated a $50 billion economic stimulus plan that includes spending on road building and other infrastructure projects, along with tax rebates of up to $1,000.