"In one week, at this defining moment in history, you can give this country the change we need," he said.
Al Jazeera's James Bays said the event was smaller than Obama's previous rallies and that despite the campaign saying it was his closing argument, there was little that was new in the speech.
Obama holds a five-point lead over McCain among likely US voters nationally in both a Reuters/C-SPAN/Zogby and in Gallup national opinion polls released on Monday.
However McCain said in Pennsylvania on Monday that electing the Illinois senator would leave a "dangerous threesome" of Democrats in charge of the US government, including Nancy Pelosi, the speaker of the house of representatives, and Harry Reid, the US senate Democratic leader.
"This election comes down to how you want your hard-earned money spent," he said.
"Do you want to keep it and invest it in your future, or have it taken by the most liberal person to ever run for the presidency and the Democratic leaders who have been running congress for the past two years?"
McCain said his approach would be to cut spending and taxes to encourage people to invest in the stock markets or buy a home.
Obama's approach, he said, would increase spending and raise taxes to pay for it.
Obama is using his huge campaign resources and thousands of volunteers to pursue to press the Arizona senator in formerly safe Republican states such as Virginia and North Carolina.
That has forced McCain to campaign in a number of states that the Republicans won comfortably in 2004, a sign, many analysts say, that he may struggle to defeat Obama on November 4.