U.S. President George W. Bush plans to press for even stricter limits on human embryo research and has no intention of softening restrictions on stem cell research, a senior administration official said on Thursday.

The official doused speculation from activists and members of Congress who hoped a brief mention of medical research in Bush’s State of the Union address on Wednesday night might mean he was being swayed by pressure from them.

“I will work with Congress to ensure that human embryos are not created for experimentation or grown for body parts and that human life is never bought or sold as a commodity,” Bush said on Wednesday night.

Supporters of embryonic stem cell research studied the brief comment for some signal of change in the policy, which limits the use of federal funds for embryo research to a few batches that existed as of August 2001.

But there was none, the official said, adding that the White House would pursue limits on other research conducted by what she called “rogue scientists.”

She referred to a 2003 experiment by Dr. Norbert Gleicher of the Foundation for Reproductive Medicine in Chicago, whose team injected male cells into female embryos.

“This would prohibit that type of experimentation as well,” the official said, adding Bush plans to lay out a detailed, broader bioethics agenda in the near future.

Colorado Democratic Rep. Diana DeGette said if Bush wants ethical medical research, he should free up federal funding, not restrict it.

“Only with the full force of the federal government, through the National Institutes of Health, can we ensure that scientific research is conducted ethically, with full respect for human life and human dignity,” DeGette, a leading proponent of embryonic stem cell research said.

Supporters of stem cell research in both the House and the Senate have said they have majorities to move ahead with legislation that would specifically authorize federal funding of the research, which doctors say has the potential to transform medicine.

Specifically, supporters say they see nothing wrong with using embryos from fertility clinics, created in the process of making “test-tube” or IVF babies, which would otherwise be discarded.

Stem cells are the body’s master cells, giving rise to tissue and organs. Stem cells from days-old embryos have the ability to form any kind of tissue and scientists are working to learn how to manipulate them to create transplants to treat diseases ranging from diabetes to Alzheimer’s to cancer.