By Wade Payson-Denney

(CNN) -- Customs and Border Protection is widening its scope for proposals to design and build the US-Mexico border wall in response to high "industry interest and feedback."

On Tuesday evening, CBP updated its pre-solicitation notice for wall designs -- and is now considering releasing two separate requests for proposals, "one focused on concrete designs, and one focused on other designs."

CBP had initially called for proposals for a 30-foot concrete wall, and intended to release its RFP by March 8. It later pushed that to "not before March 15," and now says the release of the RFPs will be "soon." Prior to this announcement, the plan was just to release an RFP based on concrete designs, but this new RFP expands the potential offerings.

There have been more than 600 indications of interest in the border-wall design process so far.

The notice maintains that "the intent of this procurement is to acquire and evaluate available wall prototypes and provide some initial construction of some wall segments, but is not intended as the vehicle for the procurement of the total wall solution for the border with Mexico."

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