... the challenge that smitty has so far failed at?
I know of no specific challenge. But yes, the left and Democrats cry racism all the time. Actual politicians.
Show me where an actual politician is actually responding to actual criticism of President Obama by calling the critic racist.
Well, most politicians are too smart to call specific things racist, because they know they can't back it up. Instead, they say that, collectively, the opposition to Obama is based on racism, bullshit like that (which Jimmy Carter infamously has done, multiple times). And the Democrats (led by DNC Chair Debbie Wasserman-Schulz) often call specific policies racist, including, but not limited to laws against abortion, promoting election integrity, promoting reductions in the welfare state, and so on (not to mention immigration).
I don't know anything about a specific challenge given, or accepted. I do know that anyone who claims the Democrats don't lie about racism all the damned time are full of shit.