There are lots of good reasons to oppose President Obama's move to grant a form of amnesty to millions of illegal aliens -- reasons that transcend anybody's position on broader issues of immigration reform.
But as we head into this battle over tying that amnesty to DHS funding and the beating Republicans are taking in the media (as always) for standing up for exceptionally important principles, I think that one particular argument could be the most effective in terms of public opinion and putting Democrats on the defensive for blocking a bill which would fund DHS but block amnesty:
Amnesty will allow illegal aliens to collect money retroactively from US taxpayers. Admittedly there are probably not very many illegals who filed tax returns, but those who did - even if they didn't pay any tax - could apply for the Earned Income Tax Credit and receive a check from the federal government.
This is insane and offensive to any American of common sense, again regardless of their view on immigration reform overall.