The British Retail Consortium has reported that more than half of high street stores will be making staff cuts this spring.
ITV Daybreak spoke to Fiona Wilson from the Union of Shop, Distributive and Allied Workers, she said: "We would expect to see some seasonal changes in the new year".
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The letter was signed by the CBI, British Chambers of Commerce, the EEF, the Institute of Directors and the Federation of Small Businesses.
A spokesperson said Rory Stewart's remarks were in line with the British government’s stated position.
The minister's intervention will come a week after Trump decertified the landmark agreement claiming it was not in the US national interest.