Trump is not a politician, he is a businessman, a deal maker if you will. He is negotiating a "deal" with republican primary voters. He's put immigration and so called "free trade" on the negotiating table. Voters have responded by putting him in second place behind Bush.
Trump is doing a masterful job of selling his "deal". It does not matter what he thought last year or even last month. He is not an ideologue, he is a pragmatist, and he is not campaigning, he is negotiating.