A revelation that Trump is a squishy moderate on immigration only hurts him in the primary, not in the general. Releasing it after Trump is the nominee might actually hurt Hillary's attempt to paint him as hard-core anti-immigrant.
Being a squishy moderate hurt Romney in the General Election. Millions of the base stayed home.
Trump is a squishy moderate, or actually, a liberal. Here’s just one example:
“Trump has long praised Mitch McConnell, the man who is the embodiment of why people are fed up with the party and attracted to Trump in the first place. While conservatives were fighting to get rid of McConnell in the 2014 primaries, Trump said, “It would be a shame if he didn’t win, because he has such power, it’s so good for his state.”
It comes as no surprise, then, that late last year Trump criticized Cruz for acting like a “maniac” when he called McConnell a liar. How does Trump plan to fight political correctness and the culture of the D.C. establishment when he has championed the mastermind of the GOP establishment and is offended by the non-politically correct criticism of its leader?”
more: https://www.conservativereview.com/commentary/2016/01/trumps-questionable-political-history