As the US Federal Reserve prepares to meet this week, storm clouds are gathering. It is widely expected that, despite protests from President Donald Trump, the Fed will raise interest rates – the latest in a series of increases which are expected to continue through to 2020.

But while most Fed officials seemed confident last month about the future prospects for the American economy, a fresh poll of economists has shown more scepticism.

The Reuters survey shows that the risk of a US recession in the next two years has risen to 40%, with suggestions that investors think growth and inflation may move the wrong way.

That 40% figure is the highest returned since the issue was put to Reuters’ survey respondents in May. Before then, it was January 2008 – eight months before the collapse of Lehman Brothers – when a comparable figure was reported.

Other Reuters polls of economists have suggested similar outcomes, strongly suggesting that upward momentum has now stopped.

The Fed is expected to raise interest rates by a quarter point this week after three rises so far this year. Another three have been mooted for next year and one more in 2020.

Not all officials in the Federal Reserve have been confident of the economic outlook, according to the minutes of the last meeting. The rate was left unchanged last month.

President Trump has been critical of the Fed’s approach and last week tried to pressurise it into not raising rates further, saying that it would be a mistake. “I think that would be foolish, but what can I say?” he said.

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By Trump’s standards, those comments were restrained. Previously, he has called the Fed “crazy”, “out of control” and “loco”. He said he was “not happy” with chairman Jerome Powell, whom he nominated to the office, and said he had not done enough to support trade negotiations around the world by setting monetary policy to support the US economy.

American presidents rarely criticise the Fed because its independence is viewed as important for US economic stability. However, Trump said he disagreed with the central bank’s policy of raising rates because it could hurt the economy, and promised to maintain his criticism if Powell continued increasing the cost of borrowing. Trump blames recent Wall Street stock market sell-offs and General Motors’ decision to lay off 14,700 people in part on Powell.

“I think he’s a good man. I think he’s trying to do what he thinks is best. I disagree with him,” Trump said last week. “I think he’s being too aggressive, far too aggressive, actually far too aggressive.”

Last month Powell said the Fed had “no preset policy path” but that in general the American economy looked robust.

As well as the announcement on rates this week, there will also be close scrutiny on the policy outlook for 2019, over which there is more uncertainty.

“There is a lot of disagreement in the markets over the Fed’s rate-hike course in 2019, with traders expecting anywhere between one and four rate hikes,” said Michael McCarthy, chief markets strategist at CMC Markets. McCarthy said markets would be watching for any revisions in the Fed’s growth and inflation outlook.