New York City Mayor Bill de Blasio is expressing dismay in a decision to delay construction on a new subway line.

The Metropolitan Transportation Authority announced that the second phase of the Second Ave. subway would be delayed beyond 2019.

The delay of that phase, which will stretch between 96th and 125th St. in Manhattan, outraged transit advocates and local officials.

De Blasio on Thursday called for the delay and the MTA’s decision to cut $1 billion from its capital plan to be “reconsidered.”

The mayor recently increased the city’s contribution to the MTA to a record $2.5 billion.

A MTA spokesman said the phase was delayed because a tunnel boring machine wouldn’t be available. The first phrase, from 63rd St to 96th St, is slated to open next year.

(AP)