Two years after the Amber Charter School opened its doors in East Harlem, the teachers decided they wanted to form a union. After a few rounds of heated negotiations with the school administration, they won the right to join the United Federation of Teachers.

Nearly four years later, none of the city’s other charters have followed in their steps. Now, with Governor Pataki pushing to allow for the creation of 150 more charter schools across the state, the union is keeping careful watch.

“What I’m seeing is that some of the charter school operators don’t want me near any of the charter school events,” the president of the UFT, Randi Weingarten, said. “What I’m seeing is lots and lots of fear on the employer side about us unionizing, and I think that that’s silly.”

Ms. Weingarten said teachers at several schools have contacted the UFT to express interest in joining the union and the UFT has made “some efforts” to start reaching out to the city’s charter schools.

About 12,000 students attend 47 charter schools across the city.

Run as independent schools, charters are typically shielded from many of the rules, regulations, and union contracts that govern regular public schools.

After years of fiercely opposing charter schools, many teachers unions across the county are now reaching out to organize educators at those schools.

The UFT even opened its own charter school in Brooklyn – the first union run charter in the country – to attempt to prove that a charter could operate smoothly under the union contract. The elementary school opened in September and the union is seeking approval to open a secondary school in the fall.

Education analysts are keeping a close eye on the UFT school to see if it will succeed.

About 1 million students nationwide now attend more than 3,600 charter schools, and about 1% of the schools operate under union contracts, the president of the Center for Education Reform, Jeanne Allen, said.

In New York City, eight schools operate under union contracts: the UFT and Amber schools and six regular public schools that converted to charters and retained their contracts.

Some charter advocates, such as Ms. Allen, argue that teacher union contracts will limit the success of charters.

“They cause difficulties because they fix into law the way teachers are allowed to operate,” Ms. Allen said. “One of the reasons traditional public school teachers flock to charters is because they have freedom they didn’t have before.”

She said union contracts make it difficult to fire bad teachers.

At the Amber Charter School on East 106th Street, the group of about 20 teachers and the board of directors agreed to a six-page contract in 2002 that they have since negotiated three times. In comparison, the general teachers’ contract is 200 pages plus hundreds of pages of supplemental agreements.

“We’ve really not had any hiccups, and we’ve gotten rid of teachers,” the vice chairman of Amber’s board, Michael Stolper, said. “Over the last few years, the city, everybody, has asked for a copy of our contract. If this story had unfolded negatively, I would be the first to say it.”

Teachers unions in several states, including New Jersey, Massachusetts, and California, have kicked off efforts to organize teachers at charter schools.

The national American Federation of Teachers, with 1.3 million members, is increasing efforts to help local districts organize.

“We as a labor organization believe that it’s our responsibility to provide representation of all employees if they’re in a regular public school or a charter school,” a spokesman for the AFT, Jaime Zapata, said. “It’s not an easy thing. This is not a big money maker for us, but we think it’s our responsibility.”

An outspoken proponent of charters, the schools chancellor, Joel Klein, has asked Albany to amend the 1998 law that allowed for the creation of charters and limited the number of such schools to 100 statewide. Mr. Pataki has suggested raising that number to 250 as part of his proposed budget. Both the Assembly and the Senate are pushing to separate the charter issue from the budget.

A Manhattan Institute fellow who has written extensively on public education and in the past has accused teacher contracts of handcuffing schools, Sol Stern, said the unionization of charters was inevitable.

“Teacher unionism is a reality,” Mr. Stern said. “If it’s fair organizing and you believe in competition as I do, what’s wrong with it? Some charter schools will unionize and others won’t. Teachers who want to go to a unionized school will go and vice versa.”