Please R-E-A-D Article ii, Section 2, Clause 2 of the Constitution. It say a treaty is ratified "provided two thirds of the Senators PRESENT concur" (emphasis added).
It can be done in the dark of night with 34 Senators. Please don't think that beyond Dirty Harry Reid's usual degree of connivance.
I would hope the pubbies are smart enough to not let that happen.
Maybe I give them too much credit? :)