(CNN) The White House on Thursday said President Donald Trump is considering a 20% tax on imports from Mexico to pay for a southern border wall, but that the President is still weighing other options.

White House press secretary Sean Spicer told reporters on Air Force One Thursday that Trump was backing the proposal and had just discussed it with congressional Republicans in a private meeting.

Hours later, amid an uproar from lawmakers on both sides of the aisle, Spicer said that he was simply putting forward one idea Trump is considering to show how the administration could fund the multibillion-dollar construction of a wall on the US's southern border. Spicer repeatedly said the White House was aiming to be "illustrative" rather than "prescriptive" as he walked back the more definitive comments he made earlier Thursday.

"Part of our goal today was to demonstrate that there is an easy way -- or several ways -- tone is to generate the reviews because the cost of the wall in the big picture is really not that significant," he said. "Imports (are) one way. I just want to be clear that we're not being prescriptive in saying that is the only way nor is the rate prescriptive."

White House chief of staff Reince Priebus also told reporters the White House is considering a "buffet of options" as it considers how to pay for the border wall.

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