They also strongly oppose human cloning for either reproductive or research purposes.
These are the chief findings of survey questions commissioned by the U.S. bishops' Pro-Life Secretariat. The questions are part of a national survey conducted by International Communications Research, which polled more than 1,000 American adults by telephone in mid-August.
The poll suggests that Americans are closely divided on federal funding of stem cell research that requires destroying human embryos, with 43% in favor and 47% opposed.
However, when given a choice between funding all stem cell research -- both adult and embryonic -- and funding only alternatives such as adult stem cell research to see if there is no need to destroy embryos for research, Americans clearly prefer funding only adult stem cell research by a margin of 61% to 23%.
Opposition to funding embryonic stem cell research is stronger among women, low-income Americans, seniors and regular churchgoers.
The survey also shows that Americans overwhelmingly oppose the use of human cloning to create embryos for medical research, 80% to 13%.
"Cloning embryos for their stem cells is the logical next step in the embryonic stem cell research agenda," says Richard Doerflinger, deputy director of the Secretariat for Pro-Life Activities. Americans also oppose cloning to provide children to infertile couples, 82% to 11%.
"Polls on embryonic stem cell research often fail to mention that the research requires destroying human embryos," said Doerflinger.
"Yet this fact is essential to understanding the moral issue," he said. "Some polls also make exaggerated claims about the [hypothetical] medical benefits of embryonic cells, while ignoring the documented benefits of alternative research that poses no moral problem. No instrument for testing public opinion should mislead the public on these crucial aspects of the issue."