It may not be as big a flop as you think. I read today, he has not finalized the plan to deal with illegal immigrants who are here and are not harmful criminals. His campaign spokesman said they are working on a plan and will announce what it will be in more detail this Thursday. It does sound like it will be a different one than just rounding up 11+ million people and deporting them.
I think he also understands he can not win with only 70% support from the Republican base. This is a move to help win some more over I think. And it may help him get more Hispanic votes. Which he needs.
I really do not care how much a candidate flip flops as long as the flips and flops are better stances. Besides, any of them will be limited by law, the Constitution and Congress what they will be able to do anyway.