Building a new rail tunnel under the Hudson River between New York City and New Jersey has been one of the nation’s top infrastructure priorities for several years. But transportation officials in the region entered the new year wondering if President Trump had decided to block the plan just as work was getting started.

The latest wrench thrown in the gears of the project, known as the Gateway Program, came Friday afternoon in the form of a letter that scuttled a funding agreement for the first phase of the project, which was estimated to cost about $11 billion. Amtrak and the states of New York and New Jersey had hoped that the federal government would cover half of that cost, but a Trump administration official disputed that notion, calling any such agreement “nonexistent.”

The letter, from K. Jane Williams, the acting administrator of the Federal Transit Administration, came just weeks after the governors of the two states outlined how they might pay for the other half of constructing a tunnel with two tracks to carry trains between Manhattan and New Jersey. The tunnel, which would supplement a pair built more than a century ago, is considered critical to maintaining a rail link between New York City and points to the south and west, including Washington.

That connection is threatened by the deteriorating conditions inside the existing tunnels, which were damaged by the floodwaters of Hurricane Sandy. The tunnels, used by Amtrak and New Jersey Transit, suffered repeated power outages last week as ice formed on the catenary wires that provide power to trains. Amtrak crews removed the ice by knocking it from the overhead wires with poles.