School and when to step in

I am really happy with the kids' school... for Lucy and for Levi. Lucy loves pretty much everything about 1st grade, and I love her teacher. Levi has adjusted well to his first year of kindergarten. For Nate, I am leaning toward unhappy. His class, unlike any other class I've been in/seen at school, is out of control. The boys especially are raucous, disrespectful, and defiant. I've gone on a couple of field trips with the class and am shocked at how these boys talk to adults. I'm finding that, while Nate's teacher is incredibly nice and is a good teacher as far as the subject matter she teaches and the ideas she has, she is unassertive and has no control over the class.

Most of these boys are pretty mean to Nate. Nate has mentioned little things here and there, but it is actually from other moms that I hear how mean these boys are. (These are usually moms of the girls in the class, who obviously tell their moms much more about school than Nate tells me.) I'm not sure how much the teacher sees/hears and how much the boys are able to keep their comments and behaviors toward Nate out of earshot/eyesight. Even if she does hear/see some of the things, I think the class has gotten so out of control that she is beyond being able to regain it.

My dilemma has been wondering when to step in. So far, I have been pretty "hands off." I have not requested extra meetings with the teacher; I haven't contacted the moms of the biggest offenders. But from what I can tell, Nate is being targeted--daily, consistently, pointedly--by multiple boys. Other moms have definitely used the words "being bullied" to me about Nate. Of course I've talked with Nate about how he should act. I know he plays at recess with Lucy, Cami, and boys/kids from other classes, so he isn't by himself during recess. I do think he reacts meanly/negatively to the boys in his class, which probably eggs them on and might also invite more meanness.

So... Do I wait out the school year in hopes they replace the current teacher (I've heard whispers here and there that this might happen)? Do I speak to the principal? At this point, I really don't see talking to the teacher doing much good; she and I have spoken on occasion, and I don't see her being able to change anything going on in the class. Do I take Nate out of school altogether and homeschool him? Do I have him repeat 3rd grade so he could be in a different class next year (I know that's really not an option, but it has crossed my mind)? I really don't know where I stand right now! I want to keep Nate at school because I value consistency and I do like this school, but I don't want to ignore an issue that has become bigger than a "hardship he can use as a growing opportunity."