NEW YORK (Reuters Breakingviews) - Every week is infrastructure week, the wags in Washington say. But the effort promised by President Donald Trump to revitalize everything from airports to schools to toll roads keeps being pushed back. It will still be up in the air in 2018.

The president has talked about mobilizing $1 trillion, though even that’s modest compared with the more than $2 trillion of infrastructure investment the American Society of Civil Engineers says is needed over the coming decade. There’s plenty of private money eager to step in, not least the $40 billion fund announced in May by Blackstone, with Saudi Arabian backing.

Some of the tax tweaks proposed by the House and Senate GOP could tilt the market in that direction. The lower chamber’s ideas include ending tax exemptions on interest income from so-called public-activity bonds, one source of funds for airport projects, for example.

Removing that subsidy, and others like it, could narrow the gap between the cost of private-sector capital and tax-exempt debt. That could allow privately funded projects to proliferate, bringing to bear cash and management expertise that’s not bogged down in federal, state or local government bureaucracy. It’s possible, though, that this type of change will be eliminated as lawmakers compromise on one bill....