Seeking to bolster their respective electoral prospects in the race for the White House, Bush and Kerry sparred on Wednesday over their public records and attacked each other on policies and priorities.
Bush criticised Kerry for his "liberal" senate record and said the challenger would raise taxes, boost spending and support more government intervention in healthcare.
Kerry hit back forcefully, stating that the American middle class had lost ground in the last four years under the president.
"I am going to stand up and fight for the American worker, and I am going to do it in a way that is fiscally sound," Kerry said.
The stakes were high for the final debate, with polls showing the race a dead heat between the two.
Kerry attacked Bush's record, saying 45 million Americans did not have health insurance, including 5 million who lost it under the president's watch.
"Being lectured by the president on fiscal responsibility is a little bit like Tony Soprano talking to me about law and order"
Bush said the challenger's alternative healthcare plan was an "empty promise" and a "bait and switch" programme that he would never be able to pay for.
"A plan is not a litany of complaints and a plan is not a programme that you can't pay for," he said.
He repeatedly attacked Kerry's senate record and accused him of supporting tax increases 98 times and voting to exceed the budget caps 277 times.
Kerry said that "anybody can play with these votes, everybody knows that" and said he had voted for tax cuts over 600 times.
"Being lectured by the president on fiscal responsibility is a little bit like Tony Soprano talking to me about law and order," Kerry said, referring to the murderous Mafia boss in a US television programme.
"This president has taken a $56 trillion surplus and turned it into deficits as far as the eye can see," he said.
"A plan is not a litany of complaints and a plan is not a programme that you can't pay for"
The Iraq issue cropped up again during the debate, with Kerry blaming Bush for rushing into war and pushing away allies.
"As a result America is now bearing this extraordinary burden where we are not as safe as we ought to be," he said. "We can do a better job of homeland security."
Bush, however, cited the elections in Afghanistan as proof that his policies were working.