President Trump's most notorious campaign promise has reached a new height of scrutiny his first full week in office. Since June 16, 2015, Trump has vowed to build a wall at the U.S. - Mexico border. 

"I will build a great, great wall on our southern border. And I will have Mexico pay for that wall," Trump said in his presidential campaign announcement. "Mark my words."

But now America appears to be financing the wall, forcing taxpayers to foot the bill. Of course, this was never explained during his presidential campaign and Trump insisted, once the news broke, that Mexico would pay the U.S. back at an unconfirmed date. 

Trump doubled down on his promise this week, referencing his upcoming meeting with Mexican President Enrique Pena Nieto, tweeting:

"Mexico's President says 'No way'; that his country is not going to pay for this wall. It's not the first time he's said it," NBC's Matt Lauer reminded President Trump’s counselor Kellyanne Conway in an interview Thursday morning. 

"So, is President Trump really going to risk funding that wall to the tune of between eight and twenty billion dollars of taxpayer money without a guarantee that we're going to get it back?" Lauer asked Conway. 

Conway insisted that Trump had been clear, despite obvious inconsistences about the payment plan. 

"He's going to build the wall, Mexico will pay for it, whether they pay for it straight out or it's reimbursed later on after congressional funding," she told Lauer.

"Let's talk about what this wall means and what the executive action yesterday really signifies," she then suggested. 

But Lauer wouldn't let Conway spin this one. 

"This payment issue, Kellyanne, is a big issue" he said, cutting her off. "We're talking about billions and billions of dollars. President Trump says we will be reimbursed, it might be in a 'complicated form'. I've got time. Explain the complicated form to me." 

"It's the 5th or 6th day on the job, Matt," Conway retorted.

"But he's had a year and a half to think about this and explain it," Lauer hammered. "You keep saying he has explained it, even as late as yesterday in that interview he said it will be in a complicated form, he didn't specifically lay it out. I'm asking you can you do that?"

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