U.S. President Donald Trump pressured Mexican President Enrique Pena Nieto earlier this year to stop publicly saying that Mexico would not pay for a planned border wall between the two countries, the Washington Post reported on Thursday.

Trump told the Mexican leader that they were both in a bit of a political bind due to Trump's campaign pledge to build a massive wall to prevent illegal immigration and have Mexico foot the bill, according to a transcript of a phone call shortly after Trump took office in January.

"They are going to say, 'who is going to pay for the wall, Mr. President?' to both of us, and we should both say, 'we will work it out,'" Trump said. "It will work out in the formula somehow. As opposed to you saying, 'we will not pay' and me saying, 'we will not pay,'" the U.S. president said.

While Trump has repeatedly insisted that Mexico would pay for the wall, he has provided few details about how that would be done.

The White House has said U.S. government will pay for the wall initially, to get the project off the ground, but that Mexico will eventually reimburse those funds.

The Post also reported details of another heated January phone call that Trump had with Australian Prime Minister Malcolm Turnbull, during which the U.S. president characterized their conversation as "ridiculous.