There's no contradiction. I am not necessarily talking about the same people. That is the point, i.e. you need to add voters (via more population in good districts or conversion of direct beneficiaries of such immigrants) and that drives your party's immigration policy. The existing base of your party, who may have very general opinions about immigration and may not really care about the specifics, will be mobilized to agree with the policy and post-hoc rationalize it.