Donald Trump has stepped up the pressure on the Federal Reserve to cut interest rates with his most personal attack yet on Jerome Powell, the man he handpicked to run the US central bank.

Ahead of a crucial speech by Powell in Jackson Hole on Friday, the US president compared the Fed chairman to a golfer who was unable to putt and said he had let the country down.

Shares on Wall Street rose at the start of the day in expectation that Powell would signal his readiness to reduce the cost of borrowing in the coming months. The Fed’s independence is supposed to be guaranteed, but the financial markets are confident it will cut interest rates at each of its next three meetings.

Trump has been using his Twitter account in recent days to fend off accusations from the Democrats that the US is heading for a recession. He has also insisted that the world’s biggest economy would be doing even better but for Powell’s mistakes.

He tweeted:

Despite the strongest growth among the G7 industrial nations and the lowest unemployment for 50 years, the Fed cut interest rates by a quarter-point last month to a range of 2%-2.25% as an insurance policy against weaker activity in the future.

Trump, however, believes Powell has been timid in his approach and cited Germany’s decision to float a 30-year bond paying no interest to investors as an example of how the Fed’s monetary policy was holding the US back.

The German bond auction proved to be something of a flop, raising only €824m (£770m) of the €2bn offered to the market. Some investors were deterred by the prospect of getting back less than they paid in 30 years’ time once inflation was taken into account.

Trump tweeted: