Rafael Carranza

The Republic | azcentral.com

With more than 640 private contractors expressing their interest in designing and building wall prototypes along the U.S.-Mexico border, U.S. Customs and Border Protection now says it is considering creating two separate categories of barrier designs.

CBP is expected to issue the request for proposals (RFP) for the project as soon as Wednesday, and award several lucrative contracts over the next few weeks. Until those RFPs are made public, it's not known exactly what kind of wall the agency will seek.

On Tuesday, though, the agency said that because of high interest in designing the prototypes, it is considering breaking down those submissions based on the materials used.

"We currently contemplate releasing two RFPs — one focused on concrete designs, and one focused on other designs," the brief update posted to the Federal Business Opportunities website reads.

It's not clear yet what the "other designs" refers to. However, it's worth noting that almost all of the nearly 700 miles of fencing already built along the U.S.-Mexico border is made of steel barriers.

Also worth noting: None of the bids will be to build "the wall" itself, along the entirety of the 1,900-mile southern border. The bidding so far will be only for prototypes, all expected to be built in Southern California.

President Donald Trump has frequently described the future wall as "big" and "beautiful," but has otherwise released very few details about what the actual barrier will look like.

As a candidate more than a year ago, he gave MSNBC one of his most detailed descriptions of the wall, although many questions about it remain.

"I'm talking about precast (concrete) going up probably 35 to 40 feet up in the air," he said. "That's high, that's a real wall. It'll look good. It'll look as good as a wall can actually look and it's gonna do the trick."

MORE: The number of border-crossers is down. Does Trump deserve the credit?

In the pre-solicitation notice posted to the Federal Business Opportunities website, CBP issued some further direction to interested bidders about the border wall prototypes.

"We anticipate procuring concrete wall structures, nominally 30 feet tall, that will meet requirements for aesthetics, anti-climbing, and resistance to tampering or damage," the post read.

But the additional post late Tuesday seemed to indicate contractors have an interest in using other materials, as well.

"To accommodate the industry interest and feedback," it wrote, the agency "intends to expand the opportunity for offerors to propose wall designs."

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