I have heard some intelligent people say they're inclined not to vote for Obama because we live in a racist country, and he can't get elected. Now, I have some problems with the whole "electability" strategy, but I don't reject that line of thinking out of hand. There are probably times when it makes sense to be strategic as a voter in that way, though I think it's a risky proposition generally, and often flawed as an approach.
But with this specific line of thinking-- "you shouldn't support Obama because others are racist"-- I would go a step further: It is, effectively, complicit with racism. It is to accept racism, rather than to fight against it.
Which is not to say those who espouse this idea are themselves racist-- not at all. However, they are deferring to a hideous attribute of our nation (and not ours alone, of course)-- which, in this case, is at least partly supposed ("I think too many people are racist for him to get elected"), rather than documented (polls don't bear it out, though I'm not sure that would matter).
How racist is our country? Hard to say, exactly. Would it prevent Obama from winning? I don't think so, but I can't prove it. I do believe, though, that allowing one's own vote to be swayed by this supposed quality in others is, essentially, to become complicit in that racism. It is to accept that tendency rather than to fight against it.
It is not racist-- obviously!-- to support someone other than Obama for the Democratic presidential nomination. Perhaps you're stirred by Edwards' embrace of the left, or by Richardson's resume, or by Dodd's focus on habeas corpus. Perhaps you think eight years as First Lady gives Clinton an important edge in experience, or that his commitment to single-payer makes Dennis Kucinich the only. These arguments are not all equal, in my opinion, but each, at least, has some merit.
The argument I refer to above does not.