Fifteen members of a group of farmworkers that staged a 1,482-mile, 80-day march from Texas to Washington to speak to President Carter began a planned 40-day hunger strike in front of the White House yesterday after failing to meet the President.

The strikers, members of the Texas Farm Workers Union, say they will live off water for as long as they can until President Carter agrees to meet them to discuss getting collective bargaining rights for want repeal of Section 14(b) of the Taft-Hartley Act banning union shop agreements between employers and unions, thereby guaranteeing "right-to-work" laws.

The farmworkers or "campesinos" have been in Washington staying in various churches in the city while waiting to meet Carter.

During the past week, organizers say, members of their group have met with several senators, congressmen and Midge Constanza, the President's assistant for public liaison, in unsuccessful attempts to arrange a meeting with Carter, who, they aretold, "will be too busy for the next three or four weeks."

Antonio Orendain, head of the union, said he is attempting to fulfill a pledge to supporters the group encountered during its journey.

"We told our supporters we would meet President Carter, and we have a moral obligation to do whatever we can to meet him," Orendain said.

The campesinos began the strike with a prayer service conducted in Spanish by Father Sean O'Malley, director of the Spanish Catholic Center on Mount Pleasant Street, after which they began petitioning spectators and passersby for signatures requesting an audience with Carter.

Orendain said that even if the strike does not produce a meeting with the President it would still get the group's message to the public.

"The people are supporting us," Orendain said, adding, "and that's why we're here."