Lawmakers in Washington delay a highly anticipated vote on an energy bill that would raise federal fuel economy standards by 40%.

Late last week, the House hammered out a compromise that would raise the corporate average fuel-economy standard to 35 mpg (6.7 L/100 km) by 2020, watering down a more strict proposal in the Senate and one many lawmakers considered the final hurdle in passing a sweeping energy bill.

But instead of voting on the bill this week as expected, House Democrats are delaying action over fears they may not have enough backing to pass the proposed legislation.

News reports cite several sticking points, including language that would require energy companies to generate 15% of their power from renewable energy sources. Republicans oppose such a measure.

Calls to Rep. John Dingell (D-MI) seeking comment were not immediately returned. Dingell chairs the House Committee on Energy and Commerce that wrote the bill.

The CAFE increase, which placates auto makers and the United Auto Workers union by keeping car and truck standards separate, appears to have a consensus, The Detroit News reports.

In addition, it appears Michigan lawmakers secured $25 billion in government-backed loans that would allow auto makers to revamp plants older than 20 years to build more fuel-efficient cars and trucks, the report says.

The House and Senate must reconcile their two energy bills before sending a final draft to President Bush for approval by the end of the year.

That process also has clouded in recent days, as the White House expresses concern over how broadly the final bill will embrace the president’s call for the use of biofuels and how clearly it defines the rulemaking roles of the National Highway Traffic Safety Admin. and the Environmental Protection Agency when it comes to fuel economy.

NHTSA presently enforces CAFE standards, but a recent court ruling allowing the EPA to govern carbon-dioxide emissions would give it a voice as well.