By Stephen Evans BBC North America business correspondent

The economy is a key issue for Ohio's voters

For Florida in 2000, read Ohio in 2004.

If there's a single state which both Democrats and Republicans feel they must win, Ohio is that state.

No Republican, including President Bush, has ever reached the White House without winning it and only two Democrats, namely Franklin D Roosevelt and John F Kennedy, have done so in the last century.

On the face of it, Ohio ought to be fertile ground for the Democratic Party's presidential candidate John Kerry.

There are big chunks of the Rust Belt there, particularly in Cleveland, and the employment situation is less than glowing.

Dilemma

Ohio has lost 230,000 jobs since Mr Bush took over and the issue of out-sourcing jobs to China and India is hot and live.

It's not enough for John Kerry and John Edwards just to say that there's been economic problems under George Bush. They need to go the next step and at least have a plausible agenda for repairing that kind of damage. Dr John Green Director of the Ray Bliss Institute at the University of Akron

Take Ohio Screw Products in Elyria just outside Cleveland, for example. If you walk the shop-floor, you'll see machines idle because the work is now done abroad.

The company's president, Dan Imbrogno, voted Republican last time but is now reserving his judgement. He can't bring himself to vote Kerry but is loathe to vote Bush.

Fear

The Republican Party accepts that it could face a tough battle. Jim Trakus, the party's chairman in the Cleveland area, says the economy is the number one issue.

Mr Kerry must come up with a solution to Ohio's economic problems

It's playing strongly with white-collar voters whom Mr Bush needs - people in finance or other office work who fear that their jobs will be done "off-shore" in India.

"There is fear in the minds of the voters," says Mr Trakus, a shrewd political thinker. "It's absolutely playing against Republicans.

"I hope that in the Republican National Convention, the president comes out and talks about these issues in order to carry any of the industrialised Midwest," Mr Trakus says.

Already declining

And yet, Ohio may yet prove not to be such a good source of votes for Mr Kerry after all. Indeed, on the ground in Cleveland it doesn't quite feel like it will.

The polls do show Mr Kerry with a sliver of a lead throughout the state, but far from enough for him to have confidence in.

And talking to people in Democratic areas reveals some doubts about Mr Kerry.

It is a common view in Cleveland that the decline of manufacturing came long before Mr Bush arrived in the White House so he can't be blamed for the current pain.

Some people point out that outsourcing happened under former President Bill Clinton too.

Quick fix

So, it is not enough for Mr Kerry just to point a finger at his rival. The economy gives Mr Kerry an opportunity but doesn't guarantee him victory.

The point is made by one of Ohio's most respected political analysts, Dr John Green, Director of the Ray Bliss Institute at the University of Akron.

Many say it is not Mr Bush's fault that manufacturing is struggling

"The lingering problem of job losses has created an opening for the Democratic candidate, making it possible for Mr Kerry to win a state with strong Republican leanings," he says.

"The task before the Democratic candidates is to exploit those economic problems by offering voters a plausible programme for recovery."

Dr Green points out that since the job loss in Ohio has been long and persistent, over 20 or 25 years, it is difficult to come up with the policy solution that is going to appeal to voters.

"It's not enough for John Kerry and John Edwards just to say that there's been economic problems under George Bush. They need to go the next step and at least have a plausible agenda for repairing that kind of damage," he says.

Which is easier said than done.

Combine that with Ohio's demographics and Mr Kerry's task seems hard. The state has large chunks of American heavy industry in it, but it also has large rural areas. It's the mix that makes it such a good barometer of American politics.

And if the industrial parts aren't swinging in droves towards Kerry, sure as eggs is eggs, neither are the agricultural counties.