A group of House Democrats said Wednesday they would push a boost in gas mileage standards for automobiles later this summer.

Both Democrats and Republicans complained that a stripped-down energy plan now under consideration by a House committee was devised to prevent them from including more ambitious proposals to raise the fuel economy standards, reduce the carbon content in fuels and promote liquefied coal as a motor fuel.

"We will pass a tough fuel economy standard soon — just as the Senate has done," said Rep. Edward Markey, D-Mass., at the start of a daylong hearing by the House Energy and Commerce Committee to consider changes to the bill.

The Senate approved a plan last week to require auto makers to increase the average fuel efficiency of their new fleets to 35 miles per gallon by 2020. Markey and several California lawmakers said they intended to seek stricter requirements when the energy proposal was considered on the House floor later this summer.

In the meantime, the bill before the House committee would improve energy efficiency of buildings and home appliances, modernize the electric grid and promote renewable fuels and electric batteries for plug-in hybrid vehicles.

Chairman John Dingell, D-Mich., said the measures "may have displeased some of our more ideologically inclined colleagues on the left and the right" but that the committee needed to move forward in areas where there was consensus.

Dingell said the committee would consider raising gas mileage standards and other energy proposals later this year as part of broad climate change legislation that aims at developing an industrywide "cap and trade" system for carbon dioxide emissions.

Republicans countered that the current bill did nothing to address the nation's energy needs, lacking measures on nuclear power, coal-to-liquid technology and oil and natural gas production.

"What do you call an energy bill that doesn't have any energy? We could call it a lethargy bill," quipped Rep. Michael Burgess, R-Texas.