The court said yesterday ( 27 June) that the Trump administration had not given a sufficient explanation for wanting to include the question.

Following the ruling, Trump said that he had sought legal advice on whether the census could be delayed.

He wrote on Twitter: "Seems totally ridiculous that our government, and indeed Country, cannot ask a basic question of Citizenship in a very expensive, detailed and important Census, in this case for 2020. I have asked the lawyers if they can delay the Census, no matter how long, until the ... United States Supreme Court is given additional information from which it can make a final and decisive decision on this very critical matter."

Trump has previously said that conducting the census without asking about citizenship would be "meaningless".

It is still possible that the question could be asked if the commerce department can provide alternative reasoning. However, it is unclear whether there is enough time to do this before the census questionnaire needs to be finalised and printed.

Howard Fienberg, vice-president of advocacy for the Insights Association, said: "We oppose the citizenship question’s addition because it hadn't undergone the rigorous testing required for any added questions. More importantly, it would jeopardise the accuracy of census data upon which nearly all the marketing research and data analytics in the United States relies for statistical benchmarking. It would negatively impact insights generation for private businesses, nonprofit organisations, and all levels of government across the country."

Fienberg added: "The Supreme Court decision is a win for accurate census data. We urge the Department of Commerce to respect this decision and immediately move ahead with 2020 Census preparations. There is no time to waste."