South Dakota Sen. Tim Johnson says the nation must take a broad approach to solving energy problems and holding down gasoline prices.
In a telephone press conference with South Dakota reporters, the Democratic senator says Republican presidential candidates are wrong to suggest that President Barack Obama is not doing enough to encourage an expansion of domestic oil production.
Johnson says oil production and drilling have increased during Obama's time as president. The senator says the U.S. cannot solve its oil problems by drilling because the nation has only 2 percent of the world's reserves.
Johnson says rising oil prices are due to global market forces and instability in some oil-producing countries.
He says the U.S. must focus on using energy efficiently and on developing ethanol and other renewable fuels.