https://www.vice.com/en_us/article/v7ved8/gas-prices-are-going-down-has-anybody-noticed

You may have noticed recently that gas prices are going down. Since mid-June, the average retail gasoline price across the U.S. has declined from a peak of $5.11 per gallon to $4.88 as of July 4, according to the U.S. Energy Information Administration, a government agency. 

This is not because of anything politicians are doing. It is because oil prices have been falling from a peak of $122 a barrel on June 8 to a low of $98 a barrel yesterday, and gasoline prices are largely based on global oil prices, something politicians cannot and do not control or significantly influence.