"Mr. Trump, how can you select as running mate someone you claimed is Constitutionally unqualified to be president and who you were threatening to sue over that very subject? What changed?"
How does Trump answer that?
He answers like this...
Because I won.
Maybe Trump could answer, he rather Cruz face being sued by Democrats as VP and battle it out in court than as President. If they lose in court, he could always replace his VP
Trump has already answered that in a previous debate; he's only attacking Cruz because Cruz is doing well in the polls and the primaries.
Trump doesn't really believe what he's saying about Cruz, or anything else. He's saying what will whip up his jackal supporters and win him the nomination.
How about, “Gaining the White House is top priority. We’ll deal with Senator Cruz’ eligibility later. Nothing has changed. I can work with anybody.”
Then let the Courts decide.