WASHINGTON - US President Donald Trump on May 11 said he backs reducing the 18.4-cent federal gasoline tax as US fuel prices shoot higher due to the Iran war and have sparked anger among American motorists.

Waiving the tax requires Congress, which is controlled by his fellow Republicans, to pass legislation.

“Yeah, I’m going to reduce,” he told reporters on whether he would suspend the tax.

Asked how long he would suspend the tax, Mr Trump, speaking in the Oval Office, replied, “till it’s appropriate”.

Senator Josh Hawley, a Missouri Republican, said he is introducing legislation on May 11 to suspend the gas tax and the 24.4-cent diesel tax for 90 days.

Gas prices have risen since the war began on Feb 28, and as Iran effectively keeps closed the Strait of Hormuz, a chokepoint through which 20 per cent of the world’s oil traditionally passes.

Gasoline prices in the US averaged US$4.52 (S$5.73) a gallon (3.78 litres) as of May 11, the highest since 2022, when the average peaked at US$5.01, according to AAA motor club.

“We’ll see where our members are,” he said.

In March, some Democrats including Senator Mark Kelly of Arizona, first proposed suspending the tax, which generates about US$2.5 billion per month in road funding, until October.

Since 2008, more than US$275 billion - including US$118 billion from the 2021 infrastructure law - has been shifted from the general fund to pay for road repairs.

Mr Trump told news outlet CBS earlier on May 11 that a bailout plan for airlines, which are struggling with surging jet fuel costs, had not “really been presented” and that “the airlines are doing not badly”.

Low-cost carriers have asked for a US$2...