By Jonathan Beale BBC News, Washington

Bush said students ought to hear different schools of thought

The president has suggested that a theory known as "intelligent design" should be taught in the classroom.

It proposes that life is too complex to have developed through evolution, and an unseen power must have had a hand.

President Bush's championing of intelligent design will be interpreted as further evidence of the growing influence of the religious right.

The US president told newspaper reporters in Texas that children should be taught about intelligent design so they could better understand the debate about the origins of the universe.

Intelligent design differs from biblical creationism in that it is not tied to a literal interpretation of the biblical book of Genesis.

Nevertheless, intelligent design points to the role of a creator, and it has become increasingly influential in Christian circles.

Scientific arguments

Yet even those on the religious right, such as Republican Senator Rick Santorum, are cautious as to how it should be taught.

"I'm not comfortable with intelligent design being taught in the science classroom," he says.

"What we should be teaching are the problems and holes, and I think there are legitimate problems and holes in the theory of evolution."

There is no science to intelligent design, it's not even a scientifically answerable question Alan Leshner AAAS

The debate, though, is already having a real impact.

In Kansas, the board of education has been re-evaluating the way evolution is taught - a sign that more conservative politicians and officials want to reflect the theory of intelligent design.

Many scientists insist, though, it is just that - a theory.

Alan Leshner, the chief executive of the American Association for the Advancement of Science, says that the proponents of intelligent design are "trying to cloak a religious concept in the mantle of science".

"There is no science to intelligent design, it's not even a scientifically answerable question," he says.

In 1925, the Scopes trial marked a defeat for creationists and opened the way for evolution to be taught in US classrooms.

Eighty years on, intelligent design is offering the creationists new comfort.