Donald Trump is considering imposing a tax on imports from Mexico to pay for a wall on the US' southern border.
White House Press Secretary Sean Spicer gave reporters in the press contingent travelling with Trump to Philadelphia some details of the proposal.
"We have a new tax at $50bn (£39.7bn) at 20% of imports – which is, by the way, a practice that 160 other countries do right now," Spicer was quoted as saying by Reuters.
"Our country's policy is to tax exports and let imports flow freely in, which is ridiculous. But by doing it that way we can do $10bn a year and easily pay for the wall. Just through that mechanism alone.
"That's really going to provide the funding," he said on the idea of a 20% tax on imports from Mexico.
"It clearly provides the funding and does so in a way that the American taxpayer is wholly respected," he added.
The idea of taxing imports from its southern neighbour is likely to further exacerbate tense relations with Mexico over the payment of the wall. President Enrique Pena Nieto cancelling a planned meeting with Trump on Thursday (26 January).
Trump told the GOP retreat the pair had reached a mutual decision to cancel the meeting, with both sides insisting the other would pay for the wall.
Spicer did not answer any questions on what an import tax would mean for US consumers – with concerns raised Mexican companies would simply pass on the 20% tax to their buyers across the border.