Wait a minute, now that I think of it, they could “Deem it”.
Using their contorted logic they would only need 2/3rds of the votes cast, not 2/3rds of the entire Senate.(Not Constitutional but hey, they can make me do business with a company I don’t already do business with)
Actually, it is.
From Art. 2 Section. 2.
He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur (where He, means the President).