Most importantly, Crimea doesn't want to be given back.
I don't know what Senator Cruz was trying to accomplish here.
How do you know that? Before the "referendum," all the polls indicated that, though the desire for being independent of Ukraine was stronger than in the East and South of Ukraine (where it is nill), they did not have a majority of people on their side, and there are millions of Crimean Tatars and Ukrainians living in Crimea.
The referendum itself was called by a "Prime Minister" who became such by walking into the Crimean Rada and declaring himself Prime Minister, and he bolstered his claim with Russkie soldiers armed with grenade launchers and machine guns.
The referendum was then conducted under wide spread intimidation, with people being tortured and even murdered, and the media entirely captured and playing and replaying propaganda. And incase that wasn't good enough, they even took the time to truck in ballots with the "yes" already marked, and had no problem letting children vote, amongst many other crooked things.
The end result was a soviet style result of an absurd super majority.
So, why do you believe that Crimea doesn't want to be given back when there has been no legitimate vote to find out?