The proposal, the official added, would have to garner the support of both Democrats and Republicans, a tall order given the vast divisions between the two parties over how to pay for such a plan at a time of rising deficits and disagreements about spending priorities. The national debt has already topped $20 trillion, and the Congressional Budget Office said on Wednesday that the nation is expected to bump up against its borrowing limit a month earlier than expected because the Treasury Department is bringing in less revenue as a result of the $1.5 trillion tax cut.

The hands-off approach is similar to the one the White House pursued with its tax cut, in which the president laid out broad parameters and drew senior lawmakers into the process of determining the details. But such a process faces long odds on infrastructure, given that Republicans are far less united on the issue and the president will not be able to rely on unified partisan support to force through a plan over the objections of Democrats.

Passing a plan through a polarized Congress, in an election year, will require “strong presidential leadership, a bipartisan effort by leaders in both parties and bringing together the broad constituency of stakeholders who will push their lawmakers to get something done,” said Ed Mortimer, the chamber’s executive director of transportation infrastructure. “That’s how we take advantage of this opportunity to do something transformational.”

Democrats say the White House has not seriously courted their input. Several Senate Democrats and their aides noted that the administration appeared to be rejecting their longstanding call for much more federal spending. “Unless we get real dollars, we will not build the infrastructure we need,” said Senator Chuck Schumer of New York, the minority leader.

White House officials said they had met with Democrats and Republicans on Capitol Hill, including members of key committees that oversee infrastructure policy. They also said they spent months meeting with mayors and state officials to determine infrastructure needs throughout the country and the funding streams available to finance them. They concluded that a larger package than Mr. Trump had initially proposed was necessary and feasible.

Administration officials say an increase in federal funds would unleash a wave of spending from cities, states and the private sector, the result of unspecified incentives in the plan. But many local and state officials have expressed concern in recent days that the administration’s faith in that potential effect is misplaced. Some Democrats and progressive groups have branded the plan a “scam,” meant to reward wealthy investors and gut environmental regulations under the guise of a job-creating, economy-juicing initiative, and said it would not prove sufficient to meet America’s need to improve roads, bridges, communications and other infrastructure.

The idea that a $200 billion federal investment would drive $1.5 trillion in total spending is “the great hocus-pocus,” said Kevin DeGood, director of infrastructure policy at the liberal Center for American Progress think tank. “There’s absolutely no evidence for that.”