Similiar to the outrage they have when homosexual activists claim their movement toward gay marriage is comparable to civil rights. That's certainly part of the problem.
Few other problems as well.
High unemployment in the black community. Telling them people outside the U.S. wil get jobs before their own doesn't sit well. Injures pride.
The same reaction any American has, that they are illegal and disrespecting our soveriegnty.
However, the biggest problem? Hispanics have surpassed the black community as the largest minority. Hispanics are not alike the black community. They voted over 40% for Bush. Black Americans voted for Bush 11%?
This means Hispanics are a more competitive demo for politicians, have greater number of votes up for grabs, and have a higher birthrate. Democrats are wiling to show them deference because of it. All the perks they used to give blacks are in danger of being given to Hispanics, and better than what was given to the black community.
This is why I've constantly told people that think the Dem monopoly on black voters can never fall, that they are wrong. better outreach by Republicans to that community, high profile applcants like Blackwell & Steele to high office, and competition from another minority group that isn't monolithic with their votes will force one of two options. 1) The loss of all their power as a voting block and the perks that comes with it. 2) A large minority vote of the black population going to Republicans. Just enough to scare the Dems into not taking them for granted.
Think of it in terms of the "free market" and it all makes sense. Either the market drives them out of power because they don't remain competitive in terms of their voting patterns OR they match their competitors and start voting Rep.
Women, white people to an extent, Hispanics, catholics..etc...all competitive blocks when pols come pandering at election time. The black community hurts itself by giving loyalty to a party that doesn't service them equally in turn.
Just look at what happened to the unions by being so solidly in the tank for Democrats.