WASHINGTON — Delivery of the US Navy's newest aircraft carrier, the Gerald R. Ford, is being delayed six to eight weeks, the service announced Tuesday, with more testing needed before the new ship can begin sea trials.

The Navy and its shipbuilder, Newport News Shipbuilding, had been driving to a delivery date of March 31, 2016. That has now slipped to mid- or late-May, a Navy spokesperson said, but a specific date will await the result of tests and trials.

Cmdr. Thurraya Kent, spokesperson for the Navy’s acquisition directorate, said in a statement that any costs associated with the delays are being "managed within budget and below the [cCongresssionally-mandated] $12.887 billion cost cap."

Kent did not detail what specific tests led to the new delays.

The Ford is 93 percent complete, according to Kent. The ship is the first of a new class of carriers that will replace the already-retired carrier Enterprise and the Nimitz-class carriers, the whose design of which dates from the 1960s. A second ship, the John F. Kennedy, already is under construction, and the third, the Enterprise, is in the earliest stages of acquisition.

Sensitivities over the new ship already are high, with an upcoming Oct. 1 hearing on the carrier program to be held by the Senate Armed Services committee. Chairman Sen. John McCain, R-Arizona, has been increasingly critical about the ship's cost, and at his direction the Navy is carrying out a study of potential alternatives to the big ship design.

The Navy's schedule to field the new ship already has been put off by a recent Pentagon direction – urged on by McCain and Michael Gilmore, director of the office of test and evaluation – to carry out full-scale shock tests on the Ford rather than perform the tests on a later ship in the class.

Opinions are divided as to how much of a delay the shock tests will have on the ship's initial operational availability, with estimates ranging from several months to as much as two years.

Here is the complete text of the US Navy statement released late Tuesday afternoon:

The Navy has identified a slight deterioration in the required progress on the CVN 78 shipboard test program. As a result, the sea trial schedule will be delayed about six to eight weeks. The exact impact on ship delivery will be determined based on the results of sea trials. CVN 78 was scheduled to deliver on March 31, 2016.    

This prudent step provides the most affordable path to delivery. All the work and any associated schedule delays are being managed within budget and below the $12,887M cost cap. 

Significant progress to date has been made on CVN 78, including:

• EMALS testing was successfully completed on the bow catapults and proceeding on schedule to complete in November on the waist catapults

• The crew moved aboard as scheduled in August and is living and feeding aboard. Compartment turnover to the crew remains on track.

• Dual Band Radar (DBR) testing has commenced including initial energization of Multifunction Radar/ Volume Search Radar (MFR/VSR) array faces

• The propulsion plants have completed their non-critical steaming program  and are preparing for their critical test program

CVN 78 is 93% complete.