I would like to nominate Nadav Rotem for the x86 backend.
Michael has indeed been doing good work over the last few months, nevertheless, I think that Nadav is presently a better choice. Especially considering that Michael will be unavailable for the next couple of weeks, it does not make sense for him to be declared code owner through the 3.2 release. As 3.3 approaches, Michael will have more experience (and more availability), and he can ask for a change.