It's conservative to defend your borders and markets. Trade Liberalization, just like open borders. isn't conservative.
Each nation must determine for itself what its interests are and to defend those interests on a case by case basis. No blank checks, No open borders.
So when you say "Free Trade leads to specialization", I point out the 3 million manufacturing jobs we've already lost. I guess you want the US worker to compete with the third world on who can work for less? Because that's what it's going to come to..
The EU would have been a free trade mechanism between those member states but they would have been extremely heavily protective against countries outside the union. Socialist no matter how they vote.