US President George W Bush and likely Democrat challenger John Kerry have traded barbed comments about the economy at their latest campaign stops.
John Kerry says the US should be tougher on trade
Correspondents say the economy is set to be a key election issue in November and is critical in several states seen as "must wins" for both men.
Mr Kerry is touring the key industrial states of Ohio, Michigan and Pennsylvania this week.
Mr Bush, meanwhile, was in Minnesota on Monday lauding new industries.
Unemployment is high in these swing states of the so-called "rust belt", which are suffering from the decline of the manufacturing industry and which collectively lost nearly 500,000 manufacturing jobs in the last four years.
Speaking in nearby West Virginia - a normally Democratic state that Mr Gore lost to Mr Bush in 2000 - Mr Kerry accused the president of failing to enforce trade agreements that protect US workers.
He said the US should be more aggressive in filing unfair trade cases at the World Trade Organisation (WTO).
"Our trade agreements ought to be enforced... [you should] put someone in charge who understands what's happening to the average worker," he told a group of coal miners at the Glen Easton colliery.
President Bush did levy duties on steel imports from Asia and Europe in an attempt to protect the US steel industry but removed tariffs when the move was ruled illegal by the WTO.
Members of the Bush campaign pointed out that Mr Kerry had voted for the North American Free Trade Agreement (Nafta), over the opposition of many unions, and accused him of flip-flopping on this issue.
While Mr Kerry was down the coal mine, President Bush was speaking in Minnesota of the importance of encouraging the spread of broadband internet connections, and called for Congress to permanently ban user taxes on people with such connections.
Mr Bush also chose to emphasise the importance of education in retraining American workers for new, better jobs.
President Bush: training will match jobs to workers
"There are jobs being created during this period of economic transition," he said. "Yet there are willing workers who don't have the skill sets necessary to fill those jobs," he told the American Association of Community Colleges.
Correspondents say Mr Bush's tactic is to appear forward-looking, concentrating on new jobs rather than protecting old ones.
And he continued to put forward an optimistic view of the future based on the success of entrepreneurs.