WASHINGTON >> President Donald Trump made rebuilding the nation’s infrastructure a major job-creating campaign pledge. But while his first big federal budget proposal has $200 billion for that purpose, most of it won’t be available until late 2018 and beyond.

And there are likely to be few specifics on the plan until fall.

White House Budget Director Mick Mulvaney on Monday reiterated Trump’s idea that every taxpayer dollar spent on infrastructure should spur on average at least $5 in investment at the state and local level. That would mean a $1 trillion investment on infrastructure over the next decade.

“There are ways to leverage federal spending in order to drive infrastructure programs at the state and local level that would not have taken place but for federal spending,” Mulvaney said.

But he did not say exactly how any of this might work, whether as public-private partnerships, tax credits, federal grants or loan programs.

Mulvaney acknowledged that some projects like ports, airports and electric transmission lines will be easy to leverage. Others, such as flood prevention, will not.

The money will not come all at once. Most of the $200 billion is slated for the second, third and fourth years of the budget, Mulvaney said. The first year, fiscal 2018, runs through Sept. 30, 2018. Trump will send his detailed budget to Congress on Tuesday. Mulvaney will appear before congressional committees to discuss the budget later in the week.

“It’s not possible to spend it all in one year, so we will allow for a ramp-up,” he said.

An emphasis on private investment had been expected, since the Republican-led Congress is unlikely to provide a substantial federal sum.