Governor Mitt Romney set off a storm of criticism Thursday after he declared in a published interview that he favored banning a specific type of stem-cell research. Scientists and the leader of the state Senate accused him of trying to block a promising avenue of research, even as anti-abortion groups assailed him for declaring that he did not object to stem-cell research involving embryos from fertility clinics.

Romney took aim at stem-cell research being planned at Harvard University, where embryos created by cloning would be used.

The governor said that he opposes "the creation of new human embryos for the purpose of research" and his aides indicated he would support criminal penalties for researchers who use new human embryos.

The governor's position was published Thursday in a New York Times article and was immediately interpreted by political analysts and some Beacon Hill politicians as an attempt to tack rightward as he eyes a possible presidential run in 2008. Romney and his aides, however, characterized it as a response to the fast-changing world of stem-cell research.

Romney has described himself as a supporter of embryonic stem-cell research since he ran for governor in 2002, and, as recently as last month, he said he would support the Legislature's efforts to promote such research in Massachusetts. But in a letter he sent to Senate President Robert E. Travaglini on Thursday, Romney said that, "respect for human life is a fundamental element of civilized society" and that "lofty goals do not justify the creation of life for experimentation and destruction."

The governor's remarks prompted Travaglini to call a news conference to criticize the governor's approach. The provost of Harvard also complained in an interview that Massachusetts could lose ground in the competition that has erupted among scientists, politicians, and private companies since California voters passed a $3 billion initiative for stem-cell research last fall.

"We are very concerned that this will create a symbolic advantage for California," said Harvard provost Dr. Steven E. Hyman. In a hastily convened news conference at the State House, Travaglini and leading stem-cell researchers said the governor's approach would diminish the chances of finding cures to dreaded diseases.

Travaglini said he wants to send a message that the medical industry is welcome in Massachusetts. "I'm disappointed that the governor has decided to send the opposite message. Rather than endorsing stem cell research, he is raising fears and unfounded doubts," he said.

"I believe that there is the potential for significant medical breakthroughs, the realization of a cure for young children with juvenile diabetes, spinal cord injury, people with Alzheimer's and Parkinson's," Travaglini said. "I believe we can put in place, and I'm confident this will be the result of the process, the necessary safeguards to ensure that this type of research is supervised and properly monitored." Dr. George Q. Daley, a stem-cell researcher on one of the Harvard teams, explained at Thursday's news conference that creating stem cells through cloning makes it much easier for scientists to study specific diseases and, perhaps, find cures for individual patients.