First question: Can you tell me what approximate population levels your mass immigration proposals will lead to? (For example, what will the total population of the USA be in 2050 if your proposals are adopted?) He or she probably either won't know the answer or if they know the answer they won't want to tell you the answer.
Second Question: Can you guarantee that there will be enough resources available to provide at least a middle class life for everyone in the USA if your particular mass immigration proposals are carried out? He or she will not have an adequate answer for you.
*Note: I'm not talking about the "Pathway to Citizenship" people here - they've already immigrated to the USA! I'm talking about future immigration.