President Bush and Mr John Kerry have tangled over health care and medical research during visits to the crucial swing states of Pennsylvania and Ohio.
With 12 days to go before the November 2nd election, President Bush condemned Mr Kerry 's health care plan yesterday as "an overpriced albatross."
Mr Kerry criticised the president's decision to limit funding for new stem cell research and said he had turned his back on science.
The Democratic candidate, who frequently touts his love for hunting and support for gun rights, courted swing voters and gun owners by donning a camouflage jacket, grabbing a shotgun and launching a predawn hunt for geese in Ohio.
He was joined on the campaign trail later by the widow of paralysed actor Christopher Reeve, who added her voice to the criticism of Mr Bush's limitation on funding for stem cell research that scientists say could be used to fight spinal cord injuries and diseases such as Alzheimer's.
"It is wrong to tell scientists that they can't cross the frontiers of new knowledge," the Massachusetts senator told supporters in Columbus, Ohio. "It is wrong morally and it is wrong economically and when I am president, we will change this policy and we will lead the world in stem cell research."
Mr Bush, in Pennsylvania, accused Mr Kerry of encouraging lawsuits against doctors and supporting a "bigger and more intrusive government" with his plan to help cover more of the 45 million Americans without health insurance.
Mr Bush said the plan would burden small businesses, restrict choices for patients and lead to more government control of Americans' health care options.
"One group looked at the plan and described it as an overpriced albatross. That's being kind," Mr Bush said. "This is a plan that will create burdens that our job creators cannot afford and do not deserve."
Neither of the candidates has been able to break away in the race, with most polls showing a dead heat or giving Mr Bush a slight edge. The latest Reuters/Zogby poll gave Bush a 46 per cent to 45 per cent lead, well within the margin of error.