Ask HN: List of government vendors in the construction industry?

I'm considering attacking a business problem for construction vendors to U.S. government agencies.

Primary vendors are the companies that deal directly with a government agency, and delegate work to sub-contractors (a sub contractor would be an electrical contractor, etc).

I'm able to get a list of all construction companies of a certain revenue, and within a few different construction segments, but "government contractor" is not a criteria I've found support for.

Any ideas?