Since US president Donald Trump hasn’t convinced Mexico to pay for the wall he wants to build between the two countries, he’s asking American payers to front (at least part of) the bill. In the budget he sent to Congress today, he’s requesting $999 million “for planning, design, and construction of the first installment of the border wall,” plus $179 million on roads, gates, and other related infrastructure.

The decision on which companies will build the wall is still far off. So far, the government has put out a tender only for prototypes for “concrete wall structures, nominally 30 feet tall, that will meet requirements for aesthetics, anti-climbing, and resistance to tampering or damage.”

Mexicans and Mexican Americans will be vying for a piece of that business. Of the roughly 700 firms that have already expressed interest in bidding to build the prototypes, about 10% are Hispanic-owned, per data from the government’s procurement system. Mexico’s cement behemoth, Cemex, said it “would gladly“ (link in Spanish) provide quotes for the mountain of cement sacks the project will require, before caving to political pressure and saying it wouldn’t take part.

Hispanics also make up nearly 30% of the US’s construction workforce, according to the Bureau of Labor Statistics. Near the border (where most US Hispanics are of Mexican descent), they’re an even larger share. Here’s the percentage of Hispanic workers in construction, farming, and extraction jobs in 2014 in the US’s four border states, according to data compiled by the Pew Research Center:

Many of these workers, moreover, are likely in the country illegally—13% of construction workers are undocumented immigrants, according to Pew. It would be one of the biggest ironies of the Trump presidency if his signature project were built by the very people it’s designed to keep out.

This story was updated on March 17 with Cemex’s decision not to be involved in the wall project.