As the price of oil neared $50 a barrel last week, an anxious Republican jokeddarkly that President George W. Bush might want to return to the lucrative oilfields of Texas. Higher prices at the pump, the former administration official added, may give him no choice.

Retail petrol prices may have slipped back in recent weeks, but in battleground states such as Ohio and other key Midwest states, the cost of a tank of petrol continues to inch upwards.