The Story thus far
In 1805, when I was but a wee child, William Paley argued for the existence of God because of the apparent design of the world. He made an analogy to a watch found on the heath, that the person finding it would surely infer the existence of the watch's designer since it's so complex. Similarly, anyone observing the complexity of the biological world would infer a designer, and Paley considered this an excellent argument for God.
In 1859, Charles Darwin and Alfred Russell Wallace presented the concept of natural selection, the first rigorous model of evolutionary change in the world. This. especially when paired with a good model of genetics, rapidly overtook the Design argument as an explanation for biological complexity.
Because people thought naturalistic explanations for biology would undermine Biblical literalism, there is a history of laws forbidding the teaching of evolution, or requiring biblical creationism to be taught. In the 1920s, Tennessee teacher John Scopes got convicted of teaching evolution, but was acquitted on a technicality. During the Cold War race for technological superiority, those laws generally fell by the wayside. In the 1980s, the Supreme Court established that there was no secular purpose served by teaching creationism, and that it wasn't science, so it couldn't be taught in science classes.
In response, several people got together and created the DIscovery Institute, organized around principles spelled out in "The Wedge Document." The idea was to renew the idea that "human beings are created in the image of God by gradually pushing materialism out of schools and society. Evolution is seen as a key promoter of materialism, so these culture warrior set their sights on that. Recognizing that science is well regarded in general, the Wedge strategy was to create a broad media driven movement to undermine the credibility of evolutionary science. One piece of the thin edge of the Wedge is "Intelligent Design" creationism.
IDC holds that there are somethings which are too complicated to have evolved without a supernatural designer at some point. They are careful not to specify who or what the designers are, nor to specify any details of the designers.
Avoiding the complexity of the scientific review process, the Discovery Institute began pushing for this new notion to be taught in schools. In 1999, the Kansas Board of Education revised science standards to remove evolution. The rest is history.
The point of this is that the attacks are not on evolution specifically. The battle in Kansas this time is over the definition of evolution, it's true, but also over whether science is the search for natural explanations of natural phenomena, or the search for any explanation. The ID advocates, who I call IDolators, see the fact that science doesn't have anything to say about the supernatural as a force for materialism and atheism.
Scientists aren't all atheists. It's a shame we have to say that up front, but there it is. Scientists don't think science can evaluate supernatural claims. We can't experiment on God, and don't want to. We study and experiment on natural phenomena. It is a bizarre form of scientism to insist that all truth must be within science, so God must fit within science. That's why this is IDolatry.
The "naturalism" that IDolators decry is no different from the everyday commitment to mechanics who look for broken parts rather than gremlins, or the generally accepted idea that the Earth will rotate around and the sun will rise each morning. The changes they want will lead to a point where, as one witness advocated, science, math, econ, art, english, and history classes would have to teach religious perspectives on the subject.
"Yes TImmy, some people think the Earth rotates so that it seems the sun moves, but others think it's the god Apollo riding in his chariot across the sky."
That's the battle.
Is there a scientific debate over evolution? No. Scientists stay employed by arguing with each other, so any serious debate would make some careers, but all the debate is about what mechanisms evolution uses, and how it has acted over different time scales, or on different planets. The attacks on evolution have been considered by scientists, and consistently found to have fatal logical flaws. Most are arguments from ignorance, which IDolators deny, as follows:
"I don't understand how evolution could have produced the flagellum, so my theory about magic pixies should be considered."
"Isn't that an argument from ignorance?"
"No, I really, really don't understand how evolution could have produced the flagellum."
And so forth.
In addition, many IDolators are intellectually dishonest, misquoting or quoting without relevant context (quotemining) to argue that scientists agree with them, when the scientists are really disagreeing. That makes it hard to take them seriously.
If you want to get more detail, check out Kansas Citizens for Science and it's associated groups like the National Center for Science Education, and state citizens for science elsewhere. TalkOrigins is a great collection of material to help understand the attacks on evolution, as is the Panda's Thumb, an associated blog.
I've been tracking this and the broader religious and cultural agenda, and I'd also recommend Ed Brayton's blog, Dispatches from the Culture Wars.