Donald Trump said on Tuesday his administration was considering suspending the federal gasoline tax, a sign the president is noticing voter anger over fuel costs a month before the midterm elections.

“We’re thinking about that,” Trump said when asked whether the tax should be suspended.

Any suspension would require an act of Congress. The president cannot unilaterally suspend the federal tax.

Trump first raised the idea in May, as the Iran war pushed fuel prices sharply higher. Pump prices have stayed high since. The national average for regular was $4.3685 a gallon on Tuesday, according to AAA, more than a dollar above where it stood a year ago.

The federal tax is 18.4¢ a gallon on gasoline and 24.4¢ on diesel. Dropping it would cut about 4% from the price of a gallon of regular. The tax also brings in more than $23bn a year for highways and public transit.

Asked about the midterms, Trump said he expected Republicans to “do very well”. He said his rallies, were “changing things around” because voters were hearing “what the Republicans have done”.

“Prices are now coming way down,” he said. “And oil, as soon as the war is over, which will be soon, will be coming way down.”

He gave no date for the end of the war and did not say how a tax suspension would pass Congress.