WASHINGTON, June 28, 2025 (BSS/AFP) - The US Federal Reserve's preferred inflation measure logged a mild uptick Friday while spending weakened, triggering another tirade by President Donald Trump against the central bank chair for not cutting interest rates sooner.

"We have a guy that's just a stubborn mule and a stupid person," Trump told an event at the White House, referring to Fed Chair Jerome Powell. "He's making a mistake."

With Powell's term as Fed chief coming to an end next year, Trump hinted at his choice of successor: "I'm going to put somebody that wants to cut rates."

The president's remarks came after government data showed the personal consumption expenditures (PCE) price index climbing 2.3 percent last month from a year ago in May.

This was in line with analyst expectations and a slight acceleration from April's 2.2 percent increase, but still a relatively mild uptick.

Excluding the volatile food and energy sectors, the PCE price index was up 2.7 percent, rising from April's 2.6 percent uptick, the Commerce Department's report showed.

But consumer spending declined, after Trump's fresh tariffs in April dragged on consumer sentiment. PCE dropped by 0.1 percent from the preceding month, reversing an earlier rise.

While Trump has imposed sweeping tariffs on most US trading partners since returning to the White House in January -- alongside higher rates on imports of steel, aluminum and autos -- these have had a muted effect so far on inflation.

This is in part because he held off or postponed some of his harshest salvos, while businesses are still running through inventory they stockpiled in anticipation of the levies.

But central bank officials have not rushed to slash interest rates, saying they can afford to wait and learn more about the impact of Trump's recent duties. They expect to learn more about the tariffs' effects over the summer.

- 'Clear weakening' -

"The experience of the limited range of tariffs introduced in 2018 suggests that pass-through to consumer prices is intense three-to-six months after their implementation," warned economists Samuel Tombs and Oliver Allen of Pantheon Macroeconomics in a note.

They flagged weakness in consumer spending, in part due to a pullback in autos after buyers rushed to get ahead of levies.

And spending on services was tepid even after excluding volatile components, they said.

"There has also been a clear weakening in discretionary services spending, notably in travel and hospitality," said Michael Pearce, deputy chief US economist at Oxford Economics, in a note.

This reflects "the chilling effect of the plunge in consumer sentiment," he added.

Between April and May, the PCE price index was up 0.1 percent, the Commerce Department report showed.

As a July deadline approaches for higher tariff rates to kick in on dozens of economies, all eyes are also on whether countries can reach lasting trade deals with Washington to ease the effects of tariffs.

For now, despite the slowing in economic growth, Pearce said risks that inflation could increase will keep the Fed on hold with interest rates "until much later in the year."