"...and not create a big Israel..."
???
Good Question!
The thought process goes like this: if we elect the right politicians, and pass the right laws, then God will heap His blessings down on us. It comes from the covenant of works that is found through Scripture. God would promise to do xyz if Israel did their part. The problem is that Israel did not, could not, do their part, and they would be hauled of to Babylon every few generations.
The problem is two-fold: like I already said, Israel could not carry out their end of the deal, so why do Evangelicals think America can. Second, the deal was with national Israel, not the US.
If we Evangelicals could get it through our collective heads that Christians are Spiritual Israel, and live like it, things would be better for our nation and for Christianity.