Minnesota state representative Ryan Winkler, a white Democrat, did not have the world's most well-thought-out response to the Supreme Court's 5–4 ruling against a key provision of the Voting Rights Act today. As you can see in the tweet above, he referred to Clarence Thomas, who voted with the majority, as "Uncle Thomas." Uncle Tom is a derogatory term used to describe "a black who is overeager to win the approval of whites (as by obsequious behavior or uncritical acceptance of white values and goals)," which is exactly how it's being used here by Winkler.
Winkler deleted the tweet and apologized, but also claims, dubiously, he didn't realize "Uncle Tom" had "racist" connotations.
I didn't think it was offensive to suggest that Justice Thomas should be even more concerned about racial discrimination than colleagues.— Ryan Winkler (@RepRyanWinkler) June 25, 2013
But if such a suggestion is offensive, I apologize.— Ryan Winkler (@RepRyanWinkler) June 25, 2013
Deleted Tweet causing offense regarding Justice Thomas. I apologize for it, but believe VRA decision does abet racism.— Ryan Winkler (@RepRyanWinkler) June 25, 2013
@atrupar I did not understand "Uncle Tom" as a racist term, and there seems to be some debate about it. I do apologize for it, however.— Ryan Winkler (@RepRyanWinkler) June 25, 2013
To be fair, there are situations when it is not racist for a white guy to call a black guy "Uncle Tom," such as when referring to an actual uncle of his named Tom, which is not what happened here, so never mind.