VIENNA, Ohio -- Casting himself as an opponent of Barack Obama, Wall Street and Washington, Sen. John McCain joined his running mate, Alaska Gov. Sarah Palin, here yesterday in a vigorous appeal for working class votes in Ohio.

Making his third campaign appearance this year in the industrial Mahoning Valley, normally a Democratic stronghold, the Senate veteran promised to rid the nation's financial markets of "reckless conduct and unbridled greed."

At the same time he accused his Democratic opponent of trying to exploit the nation's financial ills for political gain and criticized the Democrat for accepting contributions from figures associated with Fannie Mae and Freddie Mac, the two troubled mortgage institutions being brought under the financial wing of the federal government.

Earlier in the day, Mr. Obama had offered his own prescription for credit market reform in a speech in Colorado in which he derided Mr. McCain's assertion on Monday that the economy was "fundamentally sound," and ridiculed the Republican's call for a 9/11 style commission to find the roots of the current financial crisis.

As Mr. McCain spoke here, thousands of enthusiastic partisans stood elbow-to-elbow in an airplane hangar and out onto the tarmac beyond at the Youngstown-Warren Regional Airport.

Speaking before the Arizona senator, Ms. Palin assailed Mr. Obama with a series of lines reprised from her Republican National Convention acceptance speech in St. Paul, Minn., including her characterization of the Democrat as a figure "who lavishes praise on working people when they're listening, then talks about how bitterly they cling to their guns and religion when they aren't listening."

The Alaska governor assailed Mr. Obama's tax proposals, contending that they would make the economy worse.

"His tax plans really would kill jobs and hurt small business and make even today's bad economy look like the good old days," she said. Mr. McCain followed her with a full-throated denunciation of Wall Street malfeasance and the failures of Washington to counter the ills of the credit markets.

Without offering specific details, the Republican promised to bring a new spirit of openness and transparency to the regulation of financial institutions, one that would end the "wild speculation" that put financial institutions at risk.

"Americans put a lot of trust in their bankers and brokerage firms on Wall Street," Mr. McCain said. "Many leaders of finance have proven unworthy of that trust. Government has a clear responsibility to act in defense of the public interest and that's exactly what I'm going to do."

Turning to an opponent who has sought to tie Mr. McCain to policies that set the stage for Wall Street woes, he said, "Sen. Obama sees an economic crisis and he has found a political opportunity. My friends, this is not a time for political opportunism, this is a time for leadership."

In his remarks in Colorado, Mr. Obama renewed his portrait of the Republican nominee as someone out of touch with the average person and in thrall to the establishment forces that opened the door to the Wall Street panic.

"We are in the most serious financial crisis in generations. Yet Sen. McCain stood up yesterday and said that the fundamentals of the economy are strong," Mr. Obama said. "A few hours later ... he tried to explain himself again this morning by saying that what he meant was that American workers are strong.

"But we know that Sen. McCain meant what he said the first time, because he has said it over and over again throughout this campaign -- no fewer than 16 times, according to one independent count."

He pointed out that one of Mr. McCain's chief financial advisers, former Republican Sen. Phil Gramm of Texas, was a consistent champion of financial deregulation when he served in Congress.

"So it's hard to understand how Sen. McCain is going to get us out of this crisis by doing the same things with the same old players," Mr. Obama said.

In an interview yesterday morning, Mr. McCain had raised the suggestion of a 9/11-style commission to examine investment and regulatory failures.

"Sen. McCain offered up the oldest Washington stunt in the book -- you pass the buck to a commission to study the problem," Mr. Obama said.

The Mahoning Valley is normally one of the most reliably Democratic parts of Ohio. Sen. John F. Kerry carried the valley heavily against President Bush in 2004, but not many of its residents cast votes for Mr. Obama.

Sen. Hillary Rodham Clinton won the surrounding counties in a landslide in the Ohio primary that, along with a popular vote win in Texas, revived her candidacy after a string of Obama victories in February.

The Republican campaign's hopes of siphoning off normally Democratic votes in the Mahoning Valley was symbolized by the presence on stage of Jack O'Connell, a former president of the Youngstown-area AFL-CIO.

"I'm here because I believe that John McCain and Sarah Palin are honest and will do all they can to help the hard-working Ohio families," Mr. O'Connell said.

"As a lifetime union member myself, I want to give you a little straight talk of my own. They will not leave any American worker behind. ... Organized labor will have seat a the table when John McCain becomes president."

Mr. McCain offered his own note of populist solidarity in a closing shot at Mr. Obama.

"He talks about siding with the people just before he flew off for a fundraiser in Hollywood with Barbra Streisand and his celebrity friends," he said. "Let me tell you, my friends, there's no place I'd rather be than right here with the working men and women of Ohio."