"All of a sudden he's seen the light," Biden told a small crowd at Marion Harding High School in Marion in north-central Ohio.
"If John had seen the light, he would really have to acknowledge the economic crisis we're in is the final verdict on the failed economic policies of George Bush," Biden said.
Biden finished off a two-day trip through swing state Ohio on Saturday, his sixth visit here as a vice presidential candidate. Both campaigns are paying multiple visits to Ohio in the last days before Election Day.
Biden told about 2,000 supporters at Bowling Green State University that McCain and his running mate, Sarah Palin, were resorting to name calling and negative campaigning and warned that it will increase in these final days of the campaign.
"It will probably get worse," Biden said, adding that McCain was stooping to the divisive politics of former Bush aide Karl Rove.
Biden sought to assure the college students in the crowd that better days were ahead, telling them not to give up hope. He pointed out that the country was in the beginning of an unpopular war in Vietnam when he graduated from the University of Delaware in 1965.
"We've been able to overcome every obstacle in our way," he said.
Biden took a jab at McCain for getting an endorsement Saturday from Vice President Dick Cheney. "I'm not surprised. Dick Cheney has been wrong on everything else the last eight years."
Earlier in Evansville, Ind., Biden said that he and Democratic nominee Barack Obama would take a bipartisan spirit to the White House in working to revive the nation's economy and restore America's reputation in the world.
"We have to unite this country," Biden told about 1,600 people at a downtown rally. "We need to move past the political attacks that we have seen in the last few weeks of this campaign."
Biden said McCain and Palin were running an entirely negative campaign.
"They're trying to take the low road to the highest office in the land," he said. "They are calling Barack Obama every name in the book."
Biden's stop in the southwestern tip of Indiana followed a Friday night rally by Obama in northwestern Indiana that drew about 40,000 in a final weekend push in hopes of Obama becoming the first Democratic presidential candidate to win Indiana in 44 years. Three statewide polls released this week have shown the race between Obama and McCain to be in a dead heat.
In Evansville, Biden urged people to vote early, noting that they could do so after the rally at a nearby civic center.
Indiana has a record 4.5 million voters registered this year, and election officials have encouraged early voting to ease congestion at the polls on Election Day. As of Friday morning, more than 455,000 people had cast early ballots statewide, and Secretary of State Todd Rokita has predicted a record turnout for Election Day on Tuesday.
McCain has scheduled an airport rally for Monday in Indianapolis. His last previous stop in the state was on July 1, but that wasn't even an appeal to Indiana voters as he spoke to a national sheriffs convention and then to a private fundraiser in Indianapolis. Palin has made three trips to Indiana since mid-October.
Associated Press writer Mike Smith in Evansville, Ind., contributed to this report.