The U.S. average retail price for regular unleaded gasoline could drop close to $2 a gallon by late January or early February from the current national price of $2.23, the government's top energy forecasting agency said on Thursday.

The steep fall in crude oil prices, which generally account for about half the cost of making gasoline, is helping to push motor fuel prices lower. It takes about four to eight weeks for the drop in the gasoline spot prices at which gasoline is bought from refiners to be fully reflected at the pump, the federal Energy Information Administration said.

Click here to visit FOXBusiness.com's Energy Center.

"Given this time lag, it is fairly straightforward to project the direction of prices over the next week or two. That said, prices may continue to fall nationally, such that they could get close to $2 per gallon by late January or early February," the EIA said in its weekly review of the oil market.

The nearly 13 million barrel jump in gasoline stocks over the last three weeks is also pushing pump prices lower, the EIA said. "This increase in available immediate supply, combined with a seasonal drop in demand during the month of January, has put downward pressure on gasoline prices, above and beyond any downward pressure from crude oil prices," the agency said.

Click here to visit FOXBusiness.com's Energy Center.