I'm sure they won't. A senate resolution is meaningless, and a declaratory judgement requires a lawsuit with a plaintiff and a defendant. You need someone with standing to sue.
Besides there is no way Cruz would accept the offer. There's no upside for him.
“and a declaratory judgement requires a lawsuit with a plaintiff and a defendant.”
Actually it doesn’t... Look it up on Wikipedia. However, it has to be done before a suit is filed and one has. So it’s too late for that.