GOP congressional aides say Trump indicated to House Speaker Paul Ryan last week that he would veto the spending bill over money for the multibillion-dollar project, which enjoys GOP backing as well. The aides spoke on condition of anonymity to describe private conservations.
The White House would not confirm that Trump has explicitly threatened a veto.
Trump brought up the project with Ryan, R-Wis., before the start of last week's ceremony in the Capitol Rotunda commemorating Rev. Billy Graham, they said.
Trump's threat further complicates already difficult negotiations on the spending bill. Fights over abortion and Democratic opposition to Trump's U.S.-Mexico border wall are other hang-ups as closed-door negotiations on the $1.3 trillion bill are coming to a head.
There was no such veto threat when the House voted on the project last year, though the White House protested.
The House Appropriations Committee chairman, Rep. Rodney Frelinghuysen, R-N.J., is seeking a $900 million installment for the tunnel. Some lawmakers want the money spread to other projects, though the House voted in 2017 to approve the money. A Senate measure also contains money for the tunnel, though the project hasn't been as explicitly earmarked as in the House version.
Trump's home is in Manhattan and he spoke favorably of the project in a White House meeting on infrastructure last September, Schumer and other lawmakers say. At that same session, Trump took Schumer aside and offered to trade the Hudson River project for border wall money, according to a source familiar with their conversation who spoke on condition of anonymity to describe the private discussion. Schumer refused.
Schumer's position on money for the border wall has softened since he blocked it during talks last spring on a major spending bill. He has supported the money as part of legislation to offer protection to young "Dreamer" immigrants, who were brought to the U.S. illegally as children, but that effort foundered last month.
Trump's opposition to the Gateway Project is a more recent development.
"This is vitally important to the Northeast corridor and to the entire U.S. economy," Schumer said in a statement. "Jobs, income, and growth are all at stake. No one should be playing politics with it."
The White House didn't threaten to veto the tunnel when the GOP-controlled House voted on it in September. But Transportation Secretary Elaine Chao came out strongly against the money in a combative House hearing this week, telling lawmakers that New York and New Jersey need to put up a greater share of the project, which could ultimately cost $30 billion or so.
Republicans also speculated that Trump may be upset with Frelinghuysen, who opposed Trump's tax bill last year.
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.