US President Donald Trump says he wants to order the end of the constitutional right to citizenship for babies of non-citizens and unauthorised immigrants born in the United States.

The president's comments to “Axios on HBO” come amid a renewed push for hardline immigration policies before the midterm elections.

Trump believes focusing on immigration will energise his supporters and help Republicans keep control of Congress.

Revoking birthright citizenship would spark a court fight over the president's unilateral ability to change an amendment to the constitution.

The 14th Amendment guarantees that right for children born in the US.

Asked about the legality of such an executive order, Trump said “they're saying I can do it just with an executive order”.

Trump says White House lawyers are reviewing his proposal. It's unclear how quickly he would act on an executive order.