I'm going to have to eat crow here (just as I did when Reginald hit me with gospel.... literally).
Apparently, although damages may be small, free performance can result in copyright infringement, though not for infringement for profit which is another cause of action. This would seem to apply to any kind of copyrighted material, play or non.
But I would still guess that in the instance of Cruz reading Green Eggs and Ham on the Senate floor, it would not be actionable. I'm not really sure.
"10 BIG COPYRIGHT MYTHS EXPLAINED
http://www.templetons.com/brad/copymyths.html Attorney Brad Templeton selects ten "myths" and debunks them. For example, his second myth is often heard by those presenting plays in, say, a Lab Theatre environment: "If I don't charge for it, it's not a violation." Templeton makes the record clear:
False. Whether you charge can affect the damages awarded in court, but that's essentially the only difference. It's still a violation if you give it away -- and there can still be heavy damages if you hurt the commercial value of the property."