They will use the race card as long as it works. The best way to deal with it is to treat it like an accusation of child molestation.
1. If a lib calls your group racist (whites, Republicans, Tea Party, etc), call the lib crazy. Tell him such a charge is so obviously false and unprovable that it's asinine, hysterical, and to believe that he's either a radical zealot or certifiably paranoid and need psychiatric help.
2. If a lib calls YOU racist, say show the proof. If he says it's because he disgrees with you on non-racial issue X, say racism is not only irrelvant and irrational, it's a vicious slander and then either call him crazy, sue him for slander and harassment, or call him out to mutual combat ..or all 3! It's a fighting issue!