San Francisco last month joined other political entities critical of firms seeking design-build work on the Trump administration’s U.S.-Mexico border wall, with a March 21 bill to ban wall-bidders from city contracts during the bid period.

Already awarded contracts are exempt, but the ban may also include subcontractors, say media reports. Nearby Berkeley and Oakland are weighing similar measures, while California and New York are pushing statewide contract bans or pension-fund divestments against bidders. “Imposing any ban not based on contractor qualifications is preferential treatment,” said AGC of California CEO Tom Holsman on March 24. 

At least 500 design and construction sector firms and others could bid on the wall, with conceptual design bidding closed as of April 4. The final list of about 40 bidders will have 30 days to submit full proposals, says the U.S. Customs and Border Patrol.

Bidders will not include Mexican cement giant Cemex, which, despite earlier statements of interest, did not participate, a spokesman confirmed. A French politician was critical of megasupplier LaFargeHolcim CEO Eric Olsen’s stated intention to provide cement from border-state plants.

Contract awards are expected in early June, says the agency. Companies selected are set to build prototypes costing between $200,000 and $500,000 in at an undisclosed site in San Diego County on federal land within 120 ft of the border, says the San Diego Union-Tribune.

The proposed Trump budget includes $4.1 billion for the wall through 2018, but Democrats are expected to fight moves to include the money in a stopgap funding bill set for a vote by April 28 to avoid a partial government shutdown.