Rupert Cornwell: A warning for both Democrats and right-wing conservatives

This week's off-year elections sent the same lesson to both Democrats and Republicans. In the US, as in every other democracy, elections are won and lost in the centre. Parties that ignore that truth do so at their peril.

The headline losers on Tuesday were the Democrats. The gubernatorial votes in New Jersey and Virginia are being portrayed by victorious Republicans as a personal referendum on President Obama. In fact, as exit polls showed, they were nothing of the kind.

True, both states were carried by Mr Obama last year, but this time local factors were decisive; in the case of Virginia, a poor Democratic candidate matched against a good Republican, coupled with a sharp decline in turnout, especially among blacks and young people who voted for Mr Obama in huge numbers in 2008. For their part, New Jersey voters were fed up with Jon Corzine, the Democratic incumbent.

But the results are a warning to the White House – which is where the centrists come in. In both states, many of the independents, whose support was crucial for Mr Obama's success in 2008, this time backed the Republican candidate.

The main reason, predictably, was discontent with the economy, above all a jobless rate hovering at around 10 per cent, with little sign of improvement in the next few months. That spells potential trouble for Mr Obama. If the economy is still limping along come next year's mid-term elections, the Democrats could be in for a drubbing.

As it is, moderate Democrats in the House and Senate who are up for re-election in 2010 may be even more reluctant to back the current versions of healthcare reform, Mr Obama's signature issue. Word was yesterday that a final vote on the legislation may slip to next year. The closer election-day draws, the slimmer its chance of passage.

But Republicans should not gloat. The party is currently being driven by its conservative wing – symbolised by the likes of Sarah Palin and Rush Limbaugh – to the extent that in Tuesday's other significant vote, a special election in rural upstate New York, the moderate official Republican candidate found herself challenged by a conservative put up by local activists. She dropped out of the race and endorsed the Democratic candidate, handing Democrats a rock-solid Republican seat.