With crude oil prices surging to record highs above $130 a barrel, energy and environmental issues like global warming have moved to the forefront of the U.S. presidential campaign.
Here is what Republican John McCain and Democrat Barack Obama, who is close to capturing his party's nomination, are saying about energy and the environment:
Obama would cut carbon dioxide emissions to 80 percent below 1990 levels by 2050, reduce emissions to 1990 levels by 2020 and require fuel suppliers to cut carbon content by 10 percent by 2020.
McCain favors a cap-and-trade CO2 approach. He sponsored legislation in 2007 to cut emissions by 30 percent by 2050.
Obama would probe energy industry activities and stop filling the emergency oil reserve.
McCain wants to suspend the federal gasoline tax during the peak summer driving season and suspend filling of the Strategic Petroleum Reserve, a stockpile designed to ensure the United States has a cushion of crude oil to cope with major supply disruptions.
(On May 19, President George W. Bush signed a law to temporarily halt shipments to the reserve, which now holds almost 703 million barrels at four underground storage sites, until crude prices drop below $75 a barrel.)
Obama would reduce overall U.S. oil consumption by at least 35 percent, or 10 million barrels per day, by 2030 to offset imports from OPEC nations.
McCain has set no specific targets. He has said he will unveil a strategy to reduce reliance on foreign oil sources.
Vehicle Fuel Economy
Obama would double fuel economy standards in 18 years, give automakers tax credits to retool plants and invest in advanced lightweight materials and new engines.
McCain has not specified Corporate Average Fuel Economy (CAFE) targets. He voted against energy amendments in 2003 that would have boosted CAFE to 40 mpg (5.88 litres/100 km) by 2015.
Obama would boost the renewable fuel standard to at least 60 billion gallons (227 billion litres) of advanced biofuels like cellulosic ethanol by 2030, build the ethanol distribution infrastructure, mandate that all new vehicles be "flexfuel" by the end of 2012 and seek production of 2 billion gallons (9 billion litres) of cellulosic ethanol from non-corn sources like switchgrass by 2013.
McCain favors ethanol incentives after opposing them in the past. He generally opposes subsidies and tariffs that distort the marketplace.