Washington - Drivers across the United States are paying more to fill up their tanks as petrol prices continue to break records, but where Americans feel lighter pocketbooks, candidates see political fuel.

Gasoline costs averaged 3.61 dollars per gallon (about 95 cents per litre) across the country on Tuesday, and had broken 4 dollars per gallon in San Francisco and Chicago.

While those prices may still be low compared to much of the world, the increases have eaten more and more into Americans' budgets in a country that spans a continent, where wide-open spaces and sprawling suburbs leave many people with little choice but to drive to work, shop or do most anything.

The rising prices have upset truckers, who transport goods across the country and whose livelihoods are tied to the price of diesel fuel. A group of them drove to Washington Monday, with horns blaring to rally against the prices and urge politicians to take action.

But if action has seemed slow in coming, there was no shortage of words on the subject.

Democratic presidential candidate Hillary Clinton and presumptive Republican nominee John McCain have both advocated a temporary waiver of the federal sales tax on petrol. Such action would saving buyers 18.4 cents per gallon on petrol and 24.4 cents per gallon on diesel during the peak summer months, when holiday travelers typically drive up demand and prices.

Clinton's Democratic rival Barack Obama, however, has called the suggestion a "gimmick" that would drain federal highway funds and said it was designed more as a political ploy than a real solution for hard-hit voters.

Clinton and McCain have also found rare consensus on other elements of their plans to soften the blow from higher energy prices, such as ceasing additions to the strategic petroleum reserve, which holds resources in the event of an emergency that disrupts supplies. The candidates say enough oil is already being stored, and further additions are helping to drive up prices.

They differ, however, on how to pay for the petrol tax break, with Clinton suggesting a new tax on oil companies to make up the difference in revenue, but McCain making no such suggestion.

While President George W Bush has declined to weigh in on the candidates' specific plans, he has offered up suggestions of his own, urging Congress to restrain rising fuel costs in part by allowing oil exploration in an Alaskan wildlife refuge and encouraging the building of new refineries.

"One of the main reasons for high gas prices is that global oil production is not keeping up with growing demand. Members of Congress have been vocal about foreign governments increasing their oil production, yet Congress has been just as vocal in opposition to efforts to expand our production here at home," Bush told reporters Tuesday at the White House.

Bush urged Congress to consider legislation to allow oil drilling in the Alaskan National Wildlife Refuge, known as ANWAR, as an intermediate step to reduce prices before new green technologies can push down demand for petrol and lower energy prices.

Congress has been grappling with the ANWAR issue for years, under pressure from oil firms to open up the land for oil exploration of its estimated 5 billion to 16 billion barrels of oil.

Environmentalists argue that the drilling would only provide a tiny fraction of US oil needs, and want efforts to focus instead on reducing consumption. Bush has backed ANWAR drilling since taking office in 2001.

Bush also urged the building of more nuclear power plants and oil refineries. He said the reluctance to do so sends mixed signals about the US desire to lower energy prices.

Congressional Democrats put down the Bush plan as impractical and unlikely to make real change, pointing to tax incentives for big oil companies they said have hurt consumers.

"The price goes through the roof - higher, higher, higher, higher, higher, higher. And what does the president do? He takes out the old saw of ANWAR," Senator Charles Schumer, a Democrat from New York, said.

"ANWAR wouldn't produce a drop of oil in 10 years. And it's estimated that if they drilled in ANWAR, in 20 years, it would reduce the price 1 penny, and that's the president's answer to the oil crisis."

Democrats instead suggested improving energy efficiency and legislation to prevent perceived price gouging. (dpa)