President Trump’s proposed budget would cut off access to a major source of transit funding, known as New Starts. Projects that already have signed final agreements for federal funds could proceed. But others that have been working with the Federal Transit Administration, sometimes for years, would be out of luck.

“Future investments in new transit projects would be funded by the localities that use and benefit from these localized projects,” according to Trump’s spending plan.

Such a shift would leave many projects with big holes in their expected funding. Among them are a major rail project in Silicon Valley, a subway line extension in Los Angeles, a light rail line connecting Durham and Chapel Hill in North Carolina, a commuter rail project in Lake County, Indiana and a new tunnel from New Jersey to Manhattan, among other efforts.

“Without federal funds, that project would not be able to move forward,” said Mike Charbonneau, communications director for GoTriangle, the regional transit provider working on the 17.7 mile North Carolina project, which is still hoping for more than $1 billion in federal money.

Seeking to find a silver lining in all the uncertainty, Charbonneau added that “our staff feels confident that the federal budget negotiations will ultimately recognize the value of transit investment, including access to jobs and education.”

Linh Hoang, a spokeswoman for an effort to extend a Bay Area Rapid Transit District (BART) line through downtown San Jose and to the City of Santa Clara, said authorities are hearing “contradicting commitments” on infrastructure from the Trump administration.

Hoang, who works for the Santa Clara Valley Transportation Authority, pointed to Trump’s “commitments to invest $1 trillion in infrastructure vs. recommendations to cut billions of dollars from existing transportation and public transit,” saying that contrast is “of course a concern.”

Still, the process remains early and Congress is the final arbiter of what ends up in the budget, she said. “We have been working with the federal government for many years,” Hoang said. “We’re going to wait and see what the members of the House and Senate will do as they pass budget resolutions, mark up appropriations bills, vote on those bills and reconcile differences.”

Plans are still in place to ask for $1.5 billion in federal funds at year’s end. “We’re still on track,” she said.

Backers of two major projects — the Portal North Bridge across the Hackensack River and the Hudson Tunnel project, which stretches from New Jersey to Manhattan – said the proposed cuts would cause major problems.

“Zeroing out funding for New Starts will interrupt both of these critical projects and delay the start of construction, which in the case of Portal Bridge, was anticipated to begin this year,” said John D. Porcari, interim executive director of the Gateway Program Development Corporation, which is overseeing the effort.

The eventual goal of those and related projects is to dramatically increase rail capacity along the Northeast Corridor, said Porcari, a former Maryland transportation secretary and top U.S. Department of Transportation official. He called it “the most urgent infrastructure project in America.”

Here, according to the latest Federal Transit Administration data, are 16 projects that do not have the “full funding grant agreements” Trump’s budget would require for receiving the New Starts grants. If that requirement sticks, the projects would have to seek other local, state or federal sources.