"John McCain has ridden shotgun as George Bush has driven our economy toward a cliff, and now he wants to take the wheel and step on the gas," the 47-year-old said at a rally in Chester, considered to be more Republican than Democrat.
The two candidates have targeted battleground states such as Pennsylvania and Ohio as their campaigns enter the final full week before the November 4 poll.
Obama holds a comfortable lead in Pennsylvania, where McCain is seeking to win over middle-class voters who voted for Democrat Hillary Clinton over Obama in their primary battle earlier this year.
McCain, 72, sought to play on voters' fears over taxation, telling supporters in the town of Hershey: "After months of campaign trail eloquence, we've finally learned what senator Obama's economic goal is - to spread the wealth," he said.
"... Obama believes in redistributing wealth, not in policies that grow our economy and create jobs ... There's nothing 'fair' about driving our economy into the ground," he said.
McCain's poll struggle was underlined by his late decision to head to North Carolina later in the day, which has not voted for a Democratic White House hopeful since 1976 but is now a battleground state.
The two candidates are in a dead heat in the normally Republican state.
Speaking at a rally in Fayetteville, North Carolina, McCain told the crowd he was "convinced that seven days from now we will win in North Carolina".
News reports have also been circulating about tensions within the Republican camp between the McCain campaign and supporters of Sarah Palin, his vice presidential running mate.
A McCain campaigner recently called Palin a "diva", while on Tuesday, Politico.com quoted a senior McCain adviser calling her "a whack job".
McCain has denied any problems, saying he could not be more pleased with the enthusiasm Palin has generated.
Palin also told CNBC in a joint interview with McCain that "the partnership is very good".
Their Democratic rival, meanwhile, was heading to Virginia after Pennsylvania, which last backed a Democrat for the presidency in 1964 but where he now holds a double-digit poll lead.
Obama on Wednesday is set to launch an unprecedented television campaign to to push his economic rescue plans.
The Illinois senator's message will be broadcast across major networks such as CBS and NBC, as well as others like Comedy Central, and will even force a 15-minute delay in the Fox network's broadcast of the fifth game of the US baseball championship, the World Series.