Hillary Rodham Clinton on Monday criticized Barack Obama for opposing the concept of suspending the gas tax during the peak summer driving months, a plan both she and Republican John McCain have endorsed.

The idea to suspend the 18.4 cent federal gas tax and 24.4 cent diesel tax from Memorial Day to Labor Day was first proposed by McCain, the likely Republican presidential nominee, as a way to ease the economic burden for consumers during the summer.

Obama does not support the "gas tax holiday" and has said the average motorist would not benefit significantly from such a suspension; by some estimates, the federal government would lose about $10 billion in revenue.

"My opponent, Senator Obama, opposes giving consumers a break," Clinton said, campaigning in North Carolina. "I understand the American people need some relief."

Clinton said she would make up the difference in revenue by imposing a "windfall profits tax" on oil companies.

"If we suspended it and made up the lost revenues, that's the best of both worlds," she said.

Clinton commented at a firehouse in Graham, where she was urging North Carolinians to take advantage of the state's early voting, which opened more than a week ago ahead of the May 6 primary.

She and Obama have been pushing their supporters to go to the polls early here and Indiana, which also votes May 6. Obama is favored in North Carolina while the two are competing closely in Indiana.

Besides her push for early voting, Clinton was to spend part of the day raising money. She and daughter Chelsea were to appear at a closed-door fundraiser in Greensboro, with two more fundraisers scheduled later in Charlotte.

Obama also planned campaign appearances in the state, with events in Wilmington, Wilson and Chapel Hill.