WASHINGTON -- President Donald Trump has threatened to shut down the government rather than fund the Gateway Tunnel project, according to a published report.

Trump said he would veto legislation funding the government through Sept. 30 if it included money for a new tunnel linking New Jersey and Manhattan, according to Politico, which cited multiple sources.

Without a spending bill in place by March 23, federal agencies would be forced to close their doors for the third time under the Trump administration.

Trump's threat accelerated his efforts to kill the project, which he initially appeared to endorse at a White House meeting with New Jersey and New York officials last September.

Trump, a Republican, earlier pressured U.S. House Republicans to drop a $900 million allocation for Gateway, which involves building a new tunnel under the Hudson River for Amtrak and New Jersey Transit trains and replacing the Portal Bridge over the Hackensack River.

The White House did not respond to a request for comment. The White House Office of Management and Budget, which weighs in on major pieces of legislation, has yet to issue an official policy statement.

Gov. Phil Murphy, calling the project "a national economic imperative" and "a national security imperative," told reporters in West Trenton on Thursday that he expected the money to be there in the end.

"I'm still an optimist," said Murphy, a Democrat. "I still believe when something is so compelling with such broad-based support, it gets done. I assume there must be some other drama behind the curtain."

State Assembly Transportation Committee Chairman Dan Benson, D-Mercer, sharply criticized the president for opposing the tunnel project.

"It's beyond belief that the chief executive of the United States would risk both the national economy and our homeland security for any reason, let alone pure partisan politics," Benson said.

The money so far remains in the spending bill finding the government through Sept. 30, according to Matt Hadro, a spokesman for Rep. Chris Smith, R-4th Dist.

U.S. Transportation Secretary Elaine Chao claimed at a House Transportation Committee hearing Tuesday that New Jersey and New York were paying less than 5 percent of the project's cost, even though the original deal struck with President Barack Obama's administration called for the states and federal government to each pay half.

Transportation Department documents reflected the 50-50 split.

The states, though, hoped to cover part of their share through a federal loan program and pay back the money owed over 35 years.

Once the new train tunnel is built, the existing tubes can be closed temporarily to repair damage caused by Hurricane Sandy.

While objecting to the $900 million to fix Hurricane Sandy damage, Trump supported billions for repairs in southern states hit by Hurricanes Harvey, Irma and Maria last year.

Residents of those states also got special tax breaks denied to victims of Sandy.

NJ Advance Media staff writer Brent Johnson contributed to this report.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.