They will need 60 votes in the Senate and a majority in the House to put together a Compact. Case law is pretty clear that bridges are okie dokie but an increase in the states political power at the expense of the federales brings Article 1, Section 10 into play and Congress has to give the okie dokie.
I guess. The concept of a state throwing out it's vote results if people in other states votes differently... is extremely bizarre.