The price of oil has fallen as the momentum seen at the end of last week faded.
The benchmark oil contract for April delivery slipped by 55 cents to $91.40 a barrel in midday trading on the New York Mercantile Exchange.
Oil rose nearly 2% on Thursday and Friday on signs of strength in the US job market.
Many traders believe the large supply of oil in the US will keep a lid on the price.
Last week the Energy Department said that the nation's supply of crude is 10.3% above year-ago levels.
And US oil production, at more than 7 million barrels a day, is at the highest level since the late 1990s.
Jim Ritterbusch, president of energy consultancy Ritterbusch and Associates, estimates that oil supplies grew another 2.5 million barrels in the week ended March 8.
Pump prices fell slightly over the weekend. The nationwide average for a gallon of gas is $3.70, down 9 cents from a year ago.
Brent crude, used to price many kinds of oil imported by US refineries, fell 80 cents to $110.05 a barrel on the ICE Futures exchange in London.