YOUNGSTOWN, Ohio — Democratic presidential candidate Barack Obama sought on Tuesday to link the troubled economy with administration energy policies that he asserted Vice President Dick Cheney helped shape and rival Republican John McCain would continue.

"McCain has taken a page out of the Cheney playbook," Obama said as he stumped in this key battleground state.

With polls showing concern over gas prices a prime concern of Americans, Obama has been depicting energy as the nation's most pressing national security and economic issue. In that effort, he criticizes McCain as more concerned about oil company profits and drilling than an overall energy strategy.

Among other things, Obama has proposed a $1,000-per family energy rebate to be paid for by a tax on excessive energy-company profits. He called for ending U.S. reliance on oil from the Middle East and Venezuela over the next 10 years, a project he said would cost the U.S. $150 billion.

Obama has also proposed borrowing oil from the strategic petroleum reserve, a conditional and limited resumption of offshore drilling, and a new emphasis on alternative energy sources and hybrid vehicles.

"Our economy is in turmoil, I don't have to tell the people of Youngstown," Obama told a high-school gymnasium audience in this rust-belt city. "People here have known some hard knocks and hard times."

Ohio is a bellwether state, having voted for the winning candidate in all 11 presidential elections since 1964, including handing President Bush a close re-election victory in 2004.

Cheney, a former oilman, early in the Bush administration helped draft an energy policy that Obama asserted is biased in favor of tax breaks and favorable treatment for big oil. It was an attempt to capitalize on Cheney's unpopularity.

"President Bush, he had an energy policy. He turned to Dick Cheney and he said, 'Cheney, go take care of this,"' Obama said. "Cheney met with renewable-energy folks once and oil and gas (executives) 40 times. McCain has taken a page out of the Cheney playbook."

It was Obama's second day on a tour featuring a stepped-up emphasis on energy and harsher criticism of McCain.

Increasingly, with his appearances this week and with a new ad, Obama has been seeking to tie McCain to the oil and gas industry, even though McCain has no direct ties to the industry, unlike Bush and Cheney, who both worked in the industry before their election.

A new Obama ad says Big Oil filled McCain's campaign with $2 million in contributions and that he "wants to give them another $4 billion in tax breaks."

However, that consists mainly of potential revenue from a McCain proposal to lower corporate taxes on all American businesses.

The McCain campaign has also pointed out that the ad doesn't mention Obama has taken some $400,000 from oil company executives.

"We have to end the age of oil. "Obama said. "If we fail to act, there are severe indications for national security, our economy and our environment."

Obama has had trouble connecting with white working-class voters, who are a major factor in Ohio. Hillary Rodham Clinton won the state in its Democratic primary earlier this year. Gov. Ted Strickland, who had been a Clinton supporter, gave a rousing endorsement of Obama, calling him "bright, young, energized and compassionate."

Obama's focused on economic issues. He said that oil giant Exxon-Mobil "makes in 30 seconds what the typical Ohio worker makes in a year."

"We need more jobs and economic development. Why don't we focus on clean energy and reopening factories and putting people back to work? Nobody is benefiting from jobs that are leaving the community," he said.

Obama has proposed a $15-billion-a-year program to help promote clean-energy jobs.

In a question-and-answer session, Obama was asked if he would support term limits for members of Congress by a questioner who noted that many senators were elderly.

"That's kind of a tricky question. I've got colleagues in the Senate who are doing absolutely outstanding work, and they're well into their 70s," Obama said. He praised ailing Sen. Edward M. Kennedy as one.

"I'm generally not in favor of term limits," he said. "Nobody is term-limiting the lobbyists or the slick operators walking around the halls of Congress. I believe in one form of term limits. They're called elections."