If obama,and hillary are against NAFTA,why support legalizing illegal mexicans?

obama,and hillary are beating each other upside the head trying to be the strongest against NAFTA because they say it takes american jobs from americans than why not admit illegal mexicans are taking good blue collar jobs from americans not farming jobs but construction jobs i.e. framers,plumbing,a/c,concrete finishers,in texas their are nolonger,white,black,or hispanic americans doing these jobs,because they cannot compete with illegal construction crews,so why do they want to legalize illegals,why not admit,most steel jobs have left U.S. soil,because unions democrat supports have gotten greedy,in their demands,what about all the regulations democrats have forced into U.S. laws,that they do not demand other countries follow,like china a communist country,democrat ally,why not demand mexico provide for their people,instead of demanding,americans provide for mexicans,democrats are always against nonunion american voters but never admit their policys force american companys from our soil