This idea that our students need to learn both intelligent design and evolution in their science class is wrong for several reasons. The purpose of a science class, especially in a K-12 school, is to give students an understanding of the best science we have and (ideally) an idea of how science works. By itself, that is a ton of content. I have yet to meet a science teacher who actually thinks they have enough class time to fully teach all the material in their curriculum. To give you a feel for how much content there is: when I was working in a middle school in Chicago, we were given the school year to teach our sixth graders all of Earth sciences. That may sound like a ton of time but consider that Earth sciences includes: the motion of the planets, the seasons, the lunar phases, the different types of rocks, basic tectonics, earthquakes, how pressure systems impact weather, reading weather maps, what is climate, and global climate change. All this while trying to teach them how science works and give them some experience using lab materials. So as it stands many teachers don't have time to give students a good understands of the most fundamental topics. There simply isn't time for controversial or fringe science.
This brings me nicely to my second point. Intelligent design shouldn't be taught in public schools because it's not science. It makes no testable claims that could ever falsify it. I am also not aware of any scientist who has made a discovery that stemmed from their belief in intelligent design. Any paradigm which makes no testable predictions and does nothing to further our understanding of the universe really can't be called science in any meaning full way. If it's not science, then clearly it shouldn't be in taught in a science class.
If intelligent design isn't science then, what is it? Religion. The first amendment of the United States says "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof". This is in place to protect government from religion, and religion from government. So if intelligent design is religion, it cannot be taught in public schools without violation of the constitution. In 2005, this very issue came up in Dover, Pennsylvania. The judge John E Jones III concluded the following in the official decision "We have concluded that... ID cannot uncouple itself from its creationist, and thus religious, antecedents." You have a right to teach religion, just do it in church.
I have no problem with intelligent design being a part of a comparative religions course. I also think it would be really cool if maybe some larger high schools were able to offer a course on evolution that discussed the specific claims made by intelligent design proponents. Students will make up their own mind on all issues and I don't think anyone wants to stop them from doing that. What I want is for them to understand what's science, what's not, and what the difference is. That way, they will be making up their mind in an informed way. Along the same lines, how important this issue is to how you vote is up to you. I certainly am not trying to say this is the only reason to support or distance yourself from a candidate. I just find it sad when the people who are asking us to let them run this country do not understand the facts behind such a widespread issue.
If you are now sightly depressed, want to learn more, or both I highly highly recommend this clip of Dr. Neil deGrasse Tyson from his interview with Sam Ogden of Skephick.