I could be wrong, and I wasn't present obviously, but my impression is that if this subcommittee is structured the way other subcommittees are structured, the chair does not cast a vote and doesn't participate in the discussions of the committee except to try to find consensus, as opposed to advocating the point of view, if you like, of the team he is on or the party of which he is a member.
On December 4th, 2007. See this statement in context.