President Donald Trump’s administration again has set back the $1.6 billion replacement of a decrepit New York City-area rail bridge whose mechanical failures hinder train service throughout the Northeast.

About 450 trains a day, including those on Manhattan commuter lines and Amtrak’s high-speed Acela between Boston and Washington, rely on the century-old Portal Bridge, which swings to accommodate boats on the Hackensack River in New Jersey’s Meadowlands. When it fails to lock, as it did most recently in March and January, Amtrak and New Jersey Transit commuter trains are left idling.

In a July 11 letter obtained by Bloomberg, the U.S. Department of Transportation told NJ Transit it needs more time to review the bridge-funding request, which is a component of Amtrak’s proposed $30 billion Gateway project to improve the rails, bridges, stations and Hudson River tunnel it shares with commuter trains. The delay comes even after New Jersey last month agreed to borrow $600 million, double what it planned, because Trump officials said New York and New Jersey must fund a bigger share. The state also lowered its federal funding request by $33 million, to $811 million.

“Given that New Jersey Transit submitted significant changes to the cost estimate and financial plan just nine business days before the deadline, you have not allowed sufficient time for the statutorily required evaluation,” Elizabeth Riklin, a Federal Transit Administration associate administrator, wrote to Kevin Corbett, NJ Transit’s executive director.

Gateway planners had expected to have state and federal funding for the bridge in place around this time. Though New Jersey can apply for a six-month review extension, the agency already appears to have taken issue with the revisions, as “the project’s cost estimate, which FTA had previously identified as optimistic, nonetheless has been lowered in your latest submittal,” Riklin wrote.

NJ Transit declined to comment on the letter.

“We’ve submitted a strong updated financial plan with 100 percent of the local funding share committed, and will continue to work with the FTA so this vital project keeps moving forward,” Steve Sigmund, a Gateway Development Corporation spokesman, said in an email.

U.S. Senators Cory Booker of New Jersey and Chuck Schumer of New York in 2015 hailed what they called a federal funding commitment by then-President Barack Obama. Trump officials, though, have said no such plan exists—effectively throwing Gateway’s 2019 construction start date into question.

Republicans and Democrats have warned that the U.S. economy will take a hit unless improvements are made along Amtrak’s Northeast Corridor, the busiest U.S. passenger rail line, including the Portal Bridge and a second Hudson River tunnel.