Nine Democrats have announced they are vying for nomination
Democratic presidential candidate Senator Joseph Lieberman has unveiled an energy plan aimed at cutting US oil imports by two-thirds within a decade.
Under his plan, the US would reduce its dependence on foreign oil by boosting the fuel economy of passenger cars, minivans and Sports Utility Vehicles.
Mr Lieberman is one of nine Democrats to announce he is seeking the party's nomination to face President George W Bush in next year's election.
Many of the Democratic candidates are presenting policy statements in order to differentiate themselves from the other candidates, and President Bush.
"For too long our economy and our security have been at the mercy of foreign oil producers," Mr Lieberman told the Resources for the Future think tank in Washington.
"I'm not going to let foreign countries blow out our families' budgets by running up your heating bills and what you pay at the pump."
The plan stands in stark contrast to the White House's ideas, which have concentrated on developing new sources of fuel - such as highly controversial plans to drill in Alaska's wildlife reserves - rather than on fuel economy.
The difference, Mr Lieberman said, was because the Bush administration was in hock to the energy companies, with whom President George W Bush and most of his most senior cabinet members have close ties.
The US uses about 20 million barrels of oil a day, with half that amount imported.
Gasoline demand takes 40% of all oil supplies. One barrel holds 42 gallons.
Carmakers producing super-efficient vehicles that exceed the average fuel economy by at least 20%, will get pollution credits which will make it easier to meet expected new limits on greenhouse gas emissions.
"Under my plan, if one company decides to build less-efficient cars, it will be able to trade with a more efficient automaker so that the entire industry reaches our overall goal," Lieberman said.
Other parts of the senator's plan would require utilities to generate more of their electricity from renewable resources, and include a $15bn investment in clean coal technology.