And while saying that Bush and the Republicans have failed for eight years may have some impact, we won’t be running against Bush, Instead, my hunch is there’s room for an argument saying that the modern GOP won’t ever get serious about staunching illegal immigration because their main supporters, large corporations, like the supply of cheap labor. ~Ezra Klein 
This unfortunately seems right. Were any Democrats willing to try to steal the “enforcement-first” ground from the GOP, they would find a lot of success and would neutralise the Republican advantage on immigration that I discussed  before. The trouble for the Republicans is that their leadership is possibly even more terrified of appearing too “tough” on immigration than Rahm Emanuel et al. are afraid of appearing weak. It is oddly the one issue where the Republican leadership is unwilling to use voter anxiety and the appearance of Democratic “weakness” to its advantage. Klein has succinctly explained why this is. I called them the Party of Immigration for a reason.