And most importantly, they're in favor of it because the aliens in question vote Donkey after (and often before) they're granted amnesty.
Either the GOP establishment is in complete denial about this or they just don't give a damn that the vast majority of these tens of millions of new voters (many of whom are now accustomed to gov't handouts) will be voting 'Rat.
Politicians remain in power even when they're out of power. If the get voted out of office they simply get cushy CEO positions with all the stock options and a nice golden parachute upon retirement. If they're really lucky a president can simply appoint them to a position of power.