Amtrak admitted Thursday that “track problems” were to blame for its two most recent derailments, as it apologized and promised full service would be restored at Penn Station by Friday morning.

“It’s our job to make sure that all of the passengers, both on Amtrak and on our commuter partners, can travel safely and reliably,” said Amtrak President and CEO Wick Moorman said at a press conference Thursday.

“We know we let them down, quite frankly, and we are committed to make sure that that doesn’t happen again.

“I can say that we expect to have full service restored here at Penn Station by tomorrow morning.”

NJ Transit and Long Island Rail Road announced Thursday that full weekday service in and out of Penn would resume at 5:30 a.m..

An investigation found that track issues were behind the March 24 derailment and Monday’s, which caused a days-long nightmare of delays and cancellations.

The Acela train derailment nearly two weeks ago was caused by “a mismatch between two pieces of rail, and that allowed a wheel to climb one of the rails and derail,” Moorman said.

The Monday-morning rush derailment of an NJ Transit train on Track 9 “was the result of the gauge of the rails widening because there were weak timbers underneath it,” he said.

Amtrak has since taken steps to fix both issues, according to Moorman.

Stephanie Rubin, of Lyndhurst, NJ, wasn’t convinced.

“The derailments keep happening. It’s getting to the point where you almost expect it,” she said as she waited at Secaucus for a train to Penn Station. “The most frustrating part is you’re expected to still pay. It’s become your way of life.”

Late Wednesday evening, New Jersey Gov. Chris Christie halted NJ Transit’s payments to Amtrak until there was a “thorough and independent examination of the tracks, signals, switches and other equipment maintained by Amtrak” and proof that the equipment was “in a state-of-good repair,” The New York Times reported.

NJ Transit pays $2.5 million to $5 million a month for Amtrak’s operating costs and last week paid $62 million for capital investments on the Northeast Corridor line — which was supposed to be fronted by Amtrak last year.

“The recurring derailments at [Penn Station] indicate Amtrak does not take its obligations seriously and has not effectively applied NJ Transit’s considerable payments to the proper maintenance of these assets,” Christie wrote to New Jersey Attorney General Christopher Porrino.

Moorman said simply that Christie’s edict wasn’t helpful.

“I understand the governor is upset and he has a right to be upset,” he said. “I will say that withdrawing funding is not going to solve any of the problems.”

Moorman blamed soaring ridership numbers at Penn for making it tough for Amtrak to complete repairs in a timely fashion.

“One of the things, quite frankly, that slows us down is we get very, very limited amount of time for maintenance down there because our goal is not to impact service at all,” he explained.

“It is a complex place, extraordinarily busy, and, quite frankly, that’s only going to continue.”

Additional reporting by Priscilla DeGregory