And just like your typical progressive, Trump wants the courts to get involved and overrule the will of the people, and reimagine the law in his favor.
Trump is no idiot, but he acts like one, especially on this birther issue. He knows Cruz is eligible, and his continued efforts to push this issue is going to hurt him more than it will hurt Ted Cruz.
Actually, this is not a "birther" issue. The Obama birther issue centered around whether he was born in the U.S. -- that's where it became the stuff of conspiracy theorists and general loopiness. However, it is undisputed that Cruz was not born in the U.S.
So we just have the pure legal issue without the birther looniness: Is someone born abroad to at least one U.S. citizen parent a "natural born" citizen for the purposes of presidential eligibility. You'll read over and over that "most legal experts" think so. But that doesn't mean it's been decided. The only "legal experts" who count are the nine in SCOTUS.
Since when is the Constitution to be ignored because the will of the people wants to play games the easy way? The will of the people need to call an Article 5 convention and have the states ratify any changes to the Constitution’s provisions.