While a speaker would ideally refute or otherwise deal with it on the spot, it is also acceptable for them to refer the opposing member to another part of their speech (i.e., "I will be dealing with this in greater detail later in my speech.
The speaker might tackle or counter the issue on the spot, or alternatively, direct the opposing member to another part of their speech (i.e., "I will deal with this topic more comprehensively later in my discourse.