The turnaround comes after commerce secretary Wilbur Ross said on Tuesday ( 2 July) that the Census Bureau had begun the process of printing the questionnaires without the question, following a Supreme Court ruling last week.

However, Trump signalled yesterday (Wednesday 3 July) that he had not backed down on the issue. In a tweet, he said: "We are absolutely moving forward, as we must, because of the importance of the answer to this question."

The president’s reversal on the issue has cast doubt over a census that has been mired in controversy since early 2018, when it was first announced that the question would be included.

According to a New York Times report, justice department officials are now investigating whether there is a "a legally available path" to including the question.

In a court filing on Wednesday, assistant attorney general Jody Hunt said: "We at the Department of Justice have been instructed to examine whether there is a path forward, consistent with the Supreme Court’s decision, that would allow us to include the citizenship question on the census," NPR reported.

The Supreme Court ruled on 27 June that the 2020 census could not include the question on citizenship because the administration had not given a sufficient explanation for the reasons behind the plan.

Last week’s ruling left open the possibility that the question could still be asked if the commerce department was able to provide alternative reasoning, but it is unclear whether this would leave the Census Bureau with enough time to finalise and print the questionnaires.

Trump previously suggested that the administration would look at whether the census could be delayed to allow time for the addition of the question.

The constitution mandates that the count is conducted once every 10 years.