(Adds Transportation Department statement)

By Hilary Russ

NEWARK, N.J., April 19 (Reuters) - To preserve federal funding for critical rail projects, New Jersey and New York senators on Wednesday asked U.S. Transportation Secretary Elaine Chao to examine firsthand the decaying train tunnels that threaten to cripple regional travel if they fail.

In a letter to Chao, four Democratic senators, two each from New York and New Jersey, asked Chao to visit before Republican President Donald Trump's administration finalizes any federal infrastructure package.

They also urged Chao to support Amtrak's Gateway Program, which includes building a passenger rail tunnel underneath the Hudson River in partnership with NJ Transit, the two states, and their bi-state port authority.

That project, which had been fast-tracked by Chao's predecessor in the administration of former President Barack Obama, is considered one of the most important infrastructure projects in the nation.

"We're teetering every single day on the brink of truly a traffic Armageddon," U.S. Senator Corey Booker said at a news conference in Newark's Penn Station about the invitation to Chao he issued with New York senators Chuck Schumer and Kirsten Gillibrand and fellow New Jersey Senator Robert Menendez.

"The new administration has to come to the table with a commitment to what is not just a New Jersey problem, not just a regional problem, but really an American problem," Booker said.

The area is also a chokepoint on Amtrak's Northeast Corridor, a key section of rail that connects Washington to Boston.

The Transportation Department said in a statement that Chao intends to tour a number of the country’s infrastructure projects, including the Gateway site.

An important source of funding for Gateway and some other U.S. projects is uncertain because Trump proposed cutting the federal New Starts grant program in his initial budget plan.

Two NJ Transit train derailments in recent weeks, both the fault of Amtrak, badly snarled commutes. They also prompted New Jersey Governor Chris Christie, a Republican, to say he would halt state payments to the national rail operator, from which NJ Transit leases tracks.

At the news conference, a handful of protesters criticized Christie for underfunding New Jersey transportation and cancelling a previous rail tunnel project.

The governor on Wednesday blamed problems on "an absolute failure of the federal government to stand up to their obligations" to maintain infrastructure and said Amtrak is part of Chao's responsibility.

He said he had spoken to Trump about the Gateway project.

(Reporting by Hilary Russ; Editing by Lisa Shumaker)