"That means that its $35-billion risks becoming a slush fund for political priorities."

This is a very important point. But there is the potential for even greater abuse: as an actual slush fund, i.e. one for personal profit. Large government projects should be differentiated from one another with well-defined structures and objectives. These hidden "banks"/private-public-partnerships are the perfect vehicle for private parties and government cronies to extract huge amounts of money from the taxpayer without government oversight. This is the way to encourage, to "breed," a Chinese or Russian-style system of wealthy Party government/elite corporate class.

Only the ahistorical, myopic devotees of the new-left "(all/more) government is good" ideology could possibly see the benefits of opaque meshing of government with private concerns/oligarchies for their profit. If this goes through, Brazilian-style corruption and payoffs will begin in the very first year of operations.