President Donald Trump on Monday said he would criticize the Federal Reserve if it continues to raise interest rates, setting up a potential clash next month when the central bank is expected to do just that.

“I’m not thrilled with his raising of interest rates, no,“ Trump said of Fed Chairman Jerome Powell in an interview with Reuters.

Powell was nominated by Trump in November and took the helm of the central bank in early February. Since then, the Fed has hiked rates twice and has signaled that it will do so again in September.

According to Reuters, Trump said he was unhappy that other countries‘ central banks were keeping the value of their currencies low. A weaker currency makes exports cheaper and imports more expensive.

“We’re negotiating very powerfully and strongly with other nations,” Trump said. “We’re going to win. But during this period of time I should be given some help by the Fed. The other countries are accommodated.”

Asked whether he believed in the Fed’s ability to make decisions independent from political considerations, Trump said, “I believe in the Fed doing what’s good for the country.”

“Am I happy with my choice [of Powell to lead the Fed]?” Trump said to Reuters. “I’ll let you know in seven years.”

The president, a real estate mogul, has repeatedly mentioned his preference for low interest rates. He reportedly told attendees at a fundraiser on Friday that he was disappointed by the chairman, saying his advisers told him Powell liked “cheap money.”

Powell, who had already served on the Fed board for six years before becoming chairman, was seen as more sympathetic to Republican calls for a simpler rule book for banks, yet also in line with former Chair Janet Yellen on interest rate policy.

Other finalists for the job – former Fed governor Kevin Warsh and Stanford economist John Taylor – were widely expected to be more aggressive in hiking rates.

Trump openly criticized Powell for the first time in July.

In recent decades, it has been considered taboo for the president to comment publicly on the Fed‘s monetary policy decisions, though it is not without precedent.

In a speech in Sweden in May, Powell indirectly referred to a previous Fed chairman, Arthur Burns, who was pressured by President Richard Nixon in the lead-up to the 1972 presidential election to keep interest rates low.

That episode eventually contributed to a rapid rise in prices, requiring one of Burns’ successors, Paul Volcker, to raise interest rates as high as 20 percent to combat inflation.

“For a quarter century, inflation has been low and inflation expectations anchored,” Powell said at the time, in a veiled message to Trump. “We must not forget the lessons of the past, when a lack of central bank independence led to episodes of runaway inflation and subsequent economic contractions.”

Apart from the president’s opinions, the Fed faces a complex balancing act. If it raises rates too quickly, without being warranted by strong growth, it could strangle the expansion. But leaving rates low could spur out-of-control inflation. Or it could spark stability concerns by encouraging financial institutions to make riskier investments to turn a profit, since they earn less interest on loans.