WASHINGTON – Senators criticized the Bush administration’s proposal to upgrade fuel economy standards for passenger vehicles on Tuesday, contending the plan lacks the necessary urgency.

“I sense a great deal of foot dragging, reluctance and frankly … bureaucratic obstacles in this whole process,” said Sen. Olympia Snowe, R-Maine. She added, “I don’t think we can afford to rely upon bureaucratic passivity, frankly, and I think that’s what we’ve got here.”

Several senators said the White House plan fails to aggressively push automakers to improve the number of miles a car can get on a single gallon of gasoline. They noted that standards for passenger cars have remained stagnant for the past 20 years and many cited the need to demand swift numerical increases in the requirements.

“We’ve been talking now for the last four to five years and as we’ve talked, nothing has changed,” said Sen. Byron Dorgan, D-N.D., during a Senate Commerce Committee hearing.

The Bush administration’s proposal targets a 4 percent annual increase in fuel economy requirements, under a larger plan to boost alternative fuels. Automakers must currently meet a fleetwide average of 27.5 miles per gallon for passenger cars, but officials said upgraded standards could go into effect by the 2010 model year.

The proposal would also try to move to a system based on the vehicle’s dimensions, similar to reforms instituted by the National Highway Traffic Safety Administration for light trucks. By 2011, sport utility vehicles, pickups and vans must average 24.1 mpg.

But some senators panned the plan for not putting the 4 percent targeted increase in the legislation and worried that it would provide too much flexibility for lowered standards. Others were dismayed it does not take into account the potential benefits of reducing greenhouse gas emissions.

“For those who want to do nothing about fuel economy, you’re the perfect spokesman,” Sen. Barbara Boxer, D-Calif., told NHTSA administrator Nicole Nason.

Nason said the agency would seek improvements to the plan if Congress was uncomfortable with the “trust us message” that helped derail a similar proposal last year. Many lawmakers were skeptical then that NHTSA would significantly bolster the requirements.

The auto industry has said the proposal would be challenging but have offered some support for raising the standards. A government analysis, using older data, estimated the plan could cost the industry more than $100 billion.