The average price of U.S. retail gasoline dipped to $3.83 a gallon in the week ended Monday, the Energy Information Administration said in its weekly survey of service stations.

Gasoline prices have fallen more than 11 cents in the past 4 weeks, and are down more than 13 cents from a year ago, after surging to record seasonal highs earlier this year.

Expensive fuel costs had become a hot-button campaign issue ahead of the U.S. elections in November, with lawmakers seeking to score political shots over the issue.

But a drop in oil prices has stymied gasoline's march toward $4 a gallon.

Delta Air Lines said on Monday it will buy a Pennsylvania oil refinery from ConocoPhillips, further easing fears that the closure of several major East Coast refineries would cause a shortfall in gasoline or diesel supplies this summer.