NEW BRUNSWICK, N.J., May 12 - Saying that the frontiers of medical science should not be hemmed in by politics, Gov. James E. McGreevey signed legislation Wednesday to establish the nation's first state-supported stem cell research facility.

Stem cells - found in human embryos, placentas and umbilical cords - can be induced to grow into an array of different types of body tissues, and researchers say they could be useful in treating a variety of ailments. Because harvesting the cells often involves destroying a human embryo, many conservatives and anti-abortion campaigners say it is unethical.

In August 2001, President Bush forbade federal financing for research that would produce any embryonic stem cell lines other than the 64 already in existence. Today, scientists complain that there are only 15 cell lines available and that the shortage could be forestalling medical breakthroughs.

Mr. McGreevey said Wednesday that it was up to state elected officials to end the delays and help promote the kind of research that might lead to new treatments for heart disease, Alzheimer's disease, diabetes, cancer and spinal cord injuries.

"This isn't an abstract academic debate," said Mr. McGreevey, who was joined by several spinal injury victims and their families as he signed the legislation at Robert Wood Johnson Hospital in New Brunswick. "People are suffering today, and what we offer them is hope."

Mr. McGreevey's action made New Jersey the only state other than California to provide funds for the research, and came as the Bush administration faces increasing pressure to relax its restrictions. John Kerry, the presumptive Democratic presidential nominee, was an early supporter of stem cell research and has mentioned the issue often while campaigning. A letter asking the White House to allow more research was signed recently by more than 200 members of Congress, including some notable Republicans, conservatives and anti-abortion advocates.

Last week, Nancy Reagan made her first public statements in support of expanding stem cell research, saying that doing so might help treat the Alzheimer's that afflicts former President Ronald Reagan. She said it had taken him "to a distant place where I can no longer reach him."

Opposition to the research has not declined. Leaders of several national anti-abortion groups have urged the administration to provide additional funds for research that does not involve embryos and instead cultivates stem cells from the blood and bone marrow of adults.

As Mr. McGreevey arrived at the hospital Wednesday for a stem cell forum, 30 demonstrators picketed outside. Marie Tasy, public affairs director of New Jersey Right to Life, called the law the "clone and kill bill" because she said it would allow scientists to grow embryos for months, then destroy them and sell their organs to researchers.

"The pharmaceutical industry gave all this money to the administration and the Legislature because they don't want any restrictions," Ms. Tasy said, "but the language is there, and all it takes is one rogue scientist to abuse it."

The issue has also contributed to the strained relations between Mr. McGreevey, a Roman Catholic, and New Jersey church leaders, who have denounced him for supporting stem cell research, abortion rights and domestic partnership for gay couples.

Mr. McGreevey said the regulations specifically forbid cloning, and he insisted that the potential of the research outweighed the moral or ethical concerns.

The Stem Cell Institute of New Jersey is to be built near Robert Wood Johnson Hospital and is to be run jointly by Rutgers University and the University of Medicine and Dentistry of New Jersey. The governor has included $6.5 million for the institute in his budget proposal, which must be approved by the Legislature next month. Harold L. Paz, dean of the Robert Wood Johnson Medical School, said the institute was also beginning a drive for private donations but declined to say how much it hoped to raise.

About 200 researchers and health advocates attended the stem cell forum, and many said they hoped the institute would help New Jersey retain its status as a center for pharmaceutical and bio-tech research. State officials said 120 bio-tech research businesses in New Jersey employed 8,000 people and created $1 billion in revenue for the state economy.

Some families of people with incurable medical conditions were encouraged by the change. Tricia Riccio, whose teenage son was rendered quadriplegic by a wrestling accident, said she hoped research would help her son perform everyday tasks some day, like brushing his teeth.

"The disappointment of wanting to help your child and knowing there is no cure is something I hope no parent has to face," she said.