The Long Island Rail Road's largest union voted unanimously Wednesday night to authorize a strike.

The union is locked in a contract dispute with the MTA, and a work stoppage could come as early as March 21.

However, if the MTA asks the government to intervene, the strike would be pushed back to July at the earliest.

There is no word yet on if the MTA will make that special request.

The union says it has not had a pay increase in four years. In December, a Presidential Mediation Board recommended raises of 2.85 percent per year over three years. The union said it was willing to accept the increase.

However, MTA officials say they will not consider wage hikes unless they are paid for with productivity increases and higher health care contributions.