You see, the partisan view is that the president controls gas prices. If they go down, then the Republicans say it's because the economy is in the toilet because of the Democrats. The Democrats say it's down because the Democrats are doing a good job. If they go up, then the Republicans blame that on the Democrats, too, but the Democrats will say that the president has no control over the price of gas.
So, pick your team, get your pom poms ready, and cheer for your side. Meanwhile the president does not control the cost of gas regardless of whether he has a D or an R after his name, doesn't deserve any credit or any blame for fluctuating prices.
Hint: the price of gas depends on the cost of oil, which is set by the world market and depends on everything from unrest in the Middle East to decisions made by the Saudis.