He doesn’t need to. Cruz will fade away on his own.
IF he should become the candidate for pres or VP, the Dems will nail him.
And IMHO, he is not eligible. I wish Scalia was here because he was a strict constitutionalist. But here's a clue....All Presidents have been born on US soil or under US jurisdiction, i.e., Panama in the case of McCain.
That's what I'm thinking too. Plus, the timing now is wrong, at least vs. the SC race. Trump is winning, there is no benefit to suing. He could sue in the Super Tuesday states, and run a "rolling lawsuit" sort of thing as the primaries come up. I think all of that is contingent on two things - one being that Cruz comes close enough to take a significant number of delegates, and the other being that the public come to accept that Cruz's ads are misleading. I know that is using political calculus to resolve a legal issue, but the public isn't rational, and will prefer to see a lawsuit as retaliation, than as trying to follow the law.