Washington (United States) (AFP) - US consumer inflation surged to a fresh three-year high in May, with soaring energy prices caused by US President Donald Trump’s war in Iran posing a key challenge to Republicans ahead of midterm elections.

The consumer price index (CPI) rose 4.2 percent year-on-year, up from April’s 3.8 percent figure, the US Bureau of Labor Statistics said Wednesday.

It was the highest reading since April 2023, according to official data, but in line with analyst expectations.

The US-Israel war against Iran, launched in late February, has sent energy prices skyrocketing after Tehran retaliated by virtually closing the vital Strait of Hormuz, through which roughly a fifth of global oil and gas normally pass.

Asked by reporters if he was concerned by Wednesday’s data, Trump said “the numbers were great… I love the inflation.”

He repeated his prediction that it would “come down like a rock” after the conflict ends.

Economists have disputed that claim, with oil prices expected to take months to return to pre-war levels, depending on when hostilities end.

Soaring costs are a key issue for voters as they head to midterm elections in November, when Trump’s Republican Party will be aiming to maintain their control of both houses of Congress.

Should Democratic lawmakers retake one or both houses, it will limit Trump’s ability to bulldoze policies through Congress as he has done throughout his second term.

- Possible peak -

May’s consumer inflation data showed energy prices had risen 23.5 percent over the same time last year, with gasoline rising by 40.5 percent.

Grocery prices also rose significantly for the second month in a row, up 2.7 percent over a year ago.

Other prices to increase over the month included medical care, personal care, airline fares and recreation.

Americans have been dealing with years of higher prices, with inflation continuing to remain elevated long after the pandemic.

Prices have been fuelled by repeated shocks, including the Russian invasion of Ukraine, Trump’s tariffs and now the war on Iran.

Analysts, however, said that gasoline prices at the pump have recently stabilized, potentially indicating a favorable outlook for overall inflation.

“Higher energy prices again pushed up inflation last month, but we estimate that inflation has peaked and will trend lower in the second half of the year,” said Kathy Bostjancic, chief economist at Nationwide.

She added that this was assuming there was a “near-term resolution with Iran to reopen the Strait of Hormuz.”

Core CPI inflation, which excludes volatile food and energy prices, came in at 2.9 percent in May, up from 2.8 percent the month before.

“For now, there appears to be little passthrough of higher energy cost onto core inflation, outside of airfare,” said Gregory Daco, chief economist at EY-Parthenon.

- ‘No position to cut rates’ -

The US Federal Reserve has a long-term two-percent target for inflation, and the central bank’s key interest rate-setting committee will meet next week.

It will be new chairman Kevin Warsh’s first meeting since taking office last month, and he will be under pressure from Trump to reduce interest rates.

Markets, however, expect the Fed to keep rates steady at this meeting, and are now pricing in rate hikes for later in the year, spooking equity investors.

Before the war, markets had priced in rate cuts for later in the year, with expectations that inflation fueled by Trump’s tariff policy would begin to fade.

The war, however, has complicated the outlook, with more Fed policymakers saying they were concerned about rising inflation, which the central bank would typically address by raising rates.

The Fed’s preferred inflation gauge, the Personal Consumption Expenditures (PCE) prices index, also hit a three-year high in its last reading.

“The Fed will be in no position to cut rates if this continues,” said Chris Zaccarelli, chief investment officer for Northlight Asset Management.