It's not 2/3 of the Senate; it's 2/3 of SENATORS PRESENT, IOW as few as 34.
Other Freepers have pointed out that once the chief executive (POTUS) signs off on the UN bill, the bill remains in stasis just waiting for that future time when there is a 2/3 Senate majority.
Not true. Read the linked article above.
I guess there will be a lot of sleepless Republican Senators awaiting a quorum call to vote.