Republican presidential candidate Donald Trump has said he would cut off cash sent to Mexico to force them to pay for a border wall with the US.
In a memo to the Washington Post, Mr Trump writes that he would change a law to cut off money transfers to Mexico.
“It’s an easy decision for Mexico,” the candidate writes in the memo, describing it as a “one-time payment” of $5-10bn (£3.5-7bn).
Voters in Wisconsin are picking their presidential candidates.
They are going to the polls in a vote that could reshape the Republican race, with front-runner Mr Trump facing a challenge from Ted Cruz.
Asked about the memo at a campaign stop in Wisconsin, he said he stood by it.
“Absolutely, 100%,” Mr Trump told reporters. “The wall is a fraction of the kind of money in many ways that Mexico takes from the US.”
Building a border wall with Mexico has been a core message of Mr Trump’s campaign but until now he has not said how he would actually make Mexico pay for it.
Democrats are campaigning in Wisconsin ahead of the primary as well, with Hillary Clinton leading Vermont Senator Bernie Sanders in the delegate count.