It is perhaps the most audacious campaign promise of all time: the United States will build a great wall on the southern border and Mexico will pay for it. Time and again, Mexican officials have claimed they will not pay for a wall.

As a strong and vigorous supporter of President Trump, however, I believe this is one campaign promise he will certainly keep.  While cost estimates for such a wall have ranged from $10 to $25 billion, Mexico will pay for the wall, and here's one way to make it happen.

I plan to introduce the Border Wall Financing Act of 2017. I'm a firm believer in fiscally responsible infrastructure development. As with highways, the border wall should be built with a sustainable funding source. This legislation will impose a 25% surtax on any income from the sale, transfer, exchange or lease from any U.S. property owned by a Mexican national.

The revenue from this tax would be placed into a Border Wall Trust Fund. The tax would expire on the sooner of the fund accumulating $25 billion or the Mexican government directly transferring to the U.S. the necessary funds to build the wall.

Unlike other proposals, which seek to tax U.S. earnings sent back to Mexico and are largely viewed as regressive, this bill will fall primarily on Mexico's elite who are getting richer off their U.S. property investments.

For example, in 2010, Mexico's telecom baron and multibillionaire, Carlos Slim, purchased a redbrick Beaux Arts style mansion at 1009 Fifth Avenue for $44 million. Last year, it was reported that Slim was considering relisting the mansion for $80 million.

If the Border Wall Financing Act becomes law and Slim gets his asking price, he would be required to pay the 25% excise tax on the $36 million gain from the sale — a total of $9 million.  This tax would also apply to any real property income Mr. Slim accumulates in association with his ownership stake of the New York Times Building in Midtown Manhattan.

Critics might argue that this revenue raiser is a prohibited discriminatory tax. Not true. This funding mechanism is in accord with the 1992 bilateral U.S.-Mexico Income Tax Treaty. Specifically, the treaty allows for the U.S. to tax any income of a Mexican resident that is derived from the sale of immovable property (i.e. real property) located in the United States.

The fundamental purpose of the Border Wall Financing Act surtax is to give the Mexican government an incentive to pay for the wall. Once high profile wealthy Mexican elites are subject to this surtax when they sell their Vail ski chalet or Malibu mansion, they will inevitably pressure their government to pay for the wall.

A wall has already been approved by Congress. Indeed, in 2006, many Democrats joined with Republicans to vote overwhelmingly in favor of President Bush's proposal to physically secure the Mexican border.

This bill was approved by two-thirds of the House of Representatives and 80 of 100 senators — including then-Sens. Barack Obama, Joe Biden and Hillary Clinton. It ordered the Department of Homeland Security to construct about 700 miles of fencing — specifically "at least two layers of reinforced fencing" — along the southern border, as well as "additional physical barriers, roads, lighting, cameras, and sensors."

The bill directed this infrastructure to be completed within 18 months.

Over 10 years later, however, that mandate remains unfulfilled. So while Congress has already approved construction of a comprehensive border wall, the big problem has been identifying a funding source to complete it.

Congressional leaders have indicated they intend to give President Trump a variety of tools to build the wall. The Border Wall Financing Act of 2017 — a sustainable funding source that would trigger internal pressures on the Mexican government to quickly reimburse us for building the wall — would provide that key funding solution.

Renacci, a Republican, represents Ohio's 16th congressional district.