immigration is a core policy of the US that history can show we've benefitted from substantially. the inaction of politicians on the subject indicates that they feel it is the right course of action specifically to keep the cost of labor in the country low. (reference slavery, irish immigration, italians, chinese, polish, etc... and now mexican/latin american immigration). illegal immigration is the problem, and because of some of the political backlash that it raises, politicians prefer to play stupid and take no action than to stand behind tough decisions like amnesty or increased quotas for mexican and latin american migrants.
just like the other immigrants id named above, there is significant disgust for any new immigrant group among working class americans, but today's politicians dont have the guts to tell their citizen-constituents that they think making citizens or residents out of mexicans is the best thing for the country... political suicide when youre dealing with the neo-coservative base. they'll change your name to mcamnesty.
the result is that illegals arent welcomed into the ideal role of american life like the hundreds of millions of immigrants before them: not welcomed to pay income tax, learn english, make their homes here, work, etc. crime and other characteristics which could be ascribed to lack of ownership and belonging are rife.
what if 20 million aliens payed taxes?