Although all the other networks refused to call a winner, a defeat for Mr DeWine would be the first clear signal that a series of Republican corruption scandals in Ohio had turned the ultimate bellwether state into Democrat-friendly territory — for the short term at least.

According to exit polls, a Democrat also won the Ohio governorship for the first time since 1986. The polls predicted that Ted Strickland would defeat Ken Blackwell in one of 36 such races.

But perhaps of more long- term significance was the fact that Mr DeWine’s Democrat challenger, Sherrod Brown, ran as an anti-free trade protectionist, a message that appears to have attracted a significant number of blue-collar “Reagan Democrats” in the Rustbelt back to the Democrat fold.

Several other Democrat Senate candidates in close races ran as economic populists, railing against the “outsourcing” of jobs to China, signalling a protectionist lurch for the party.

On one level, Ohio was always going to be one of the most difficult states for Republican candidates this year because the local party has been beset by sleaze. The outgoing governor, Bob Taft, pleaded guilty last year to violating state ethics laws and Bob Ney, a senior congressman, admitted last month corruption charges linked to the Jack Abramoff lobbying scandal. A Republican fundraiser with links to Mr Taft is also under investigation.

But Ohio also sits in the heart of the Midwest, a region where the economy is arguably an even bigger issue than Iraq. Although the US economy overall is performing well, the Midwest has lost many manufacturing jobs, particularly in the car industry, which in the past year has slashed its workforce.

In Ohio, the unemployment rate is over a point above the national average, at 5.7 per cent, and the state has recorded a net job loss of 150,000 since 2001. Car plants and factories have also closed, or seen major job losses, across the Midwest, in states such as Michigan, Illinois, Iowa and Wisconsin.

Reagan Democrats have been a cornerstone of Republican electoral success for a generation, especially in the Midwest. By the early 1980s, these white, blue collar, socially conservative voters had ceased to regard the Democrats as their champions. In 1980 millions fled to Ronald Reagan and have stayed with the Republicans ever since — notably handing victory to President Bush in 2004.

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