Gasoline prices are heading downward nationwide, and the decline is especially sharp in several swing states in the White House contest, including the prized battleground of Ohio.

The trend is likely a relief to President Obama’s campaign. But prices remain high by historical standards as Mitt Romney continues to hammer the president over drivers’ pain in the race’s homestretch.

The nationwide average for regular gasoline fell by 12 cents over the last week to $3.67 per-gallon Monday, the largest week-over-week decline since 2008, according to AAA.

“AAA expects that gas prices across the country will continue to drop leading up to Election Day and will move even lower approaching the end of the year, barring any unforeseen forces,” said Avery Ash, AAA’s manager of regulatory affairs, in his weekly analysis. He expects average prices in the range of $3.40 to $3.50 per gallon on Election Day.