First, whoever brought up race here did so without any good reason for it other than being a racist or an unsuccessful comedian.
Second,
The far right-wing of the GOP is pretty fuckin savvy. They will co-opt Black politicians purely to dodge the claims of racism, and a lot of racist whites will vote for Black or brown Republicans if they are sufficiently "Uncle Tomish" and willing to attack at least some vulnerable minority in this country-- gays, Muslims, whatever. And a lot of racists aren't necessarily racist against Black folk anymore. It's not like the old days. The popular targets nowadays are Hispanics, people from Muslim countries, immigrants in general and gays. Blacks not as much nowadays--and to the extent Black Americans still are subject to institutional discrimination in this country, electing Black politicians is not necessarily a threat to that. As long as the politician supports the Drug War and the prison-industrial complex the most serious racism against Black folks in society nowadays will remain, no matter who the color of those in charge are.
Which college did you study at? You may want to ask for your money back if they taught you American politics.
I want to start by saying that I go through my life in USA almost without any need to use words black or white to label people. I say almost, because police officers, I have discovered, are not amused at all when one tries to use any other word than "black" to describe someone, who would be seen by most as black. It's a personal choice and I am certainly not a good representative of D.C in this respect. Many Americans are obsessed with the words black and white. Asian, Indian and other labels are less popular in my village. To reply to the post above, however, I have to use the labels.
I am leaning towards voting for Democrats on most of the issues, but to say that Republicans co-opt black people to avoid being called racists is childish. Who do Republicans represent? They are elected by those who oppose abortion and they represent the very rich. Who are traditionally very rich in USA? Few white people. Are white people traditionally racist in USA? Of course, as are black, yellow and purple people. Thus above misunderstanding about otherwise "unexplainable membership" of black people in GOP.
Both parties are equally cynical and want most votes, which means that they need to reach out to all colors of voters. The reason Republicans are more obsessed with illegal immigrants is because, unlike democrats, they don't care about paying extra few bucks to a native white American to mow their lawn instead of using a cheaper illegal laborer from Mexico.
Remember Condoleezza Rice? Do you know why she's a Republican? Because when her dad wanted to vote for the Democratic party, he was refused that right by democrats for being black and so joined Republicans who did not push him away, long before issue of Mexicans arose.
I have no clue about British politics, but it seems that the parallels are not there when it comes to race.