Upping the ante in the battle over Amtrak funding, union leaders Wednesday threatened a one-day shutdown of Amtrak Oct. 3 to protest plans by the White House and Republicans in Congress to give the rail line less money than they say it needs.

Amtrak officials, who also have been pushing the White House to greatly increase federal subsidies for the national passenger railroad, said they would seek a court order to prevent the work stoppage.

“We are going to give the White House and Republicans in Congress a one-day snapshot of what this nation would be like without Amtrak,” said Charles Moneypenny, director of the railroad division of the Transportation Workers Union of America, speaking for about 8,000 Amtrak employees.

Amtrak workers have tried such a tactic several times before, only to be ordered back to work by the courts.

Wednesday’s announcement marked yet another escalation in the conflict between advocates of greatly increased spending for Amtrak and critics who contend that Amtrak is a bloated relic that has not responded to changing American travel patterns.

Congress is expected to finish its work on the Amtrak budget just as the unions prepare for their walkout.