Play the race card
To attempt to gain advantage in an election by pandering to the electorate's racism. Also, more recently, to attempt (by a black person) to gain advantage by accusing another (usually a white person) of racism.
This term is now more often used in the USA than in other countries, but was coined in England in the 1960s. It alludes to the playing of a trump card in card games like whist.
Following an influx of immigrants into the UK in the 1950/60s there was known to be a degree of racist discontent amongst the (largely white) indigenous population. Reputable politicians avoided acknowledging this openly and there was an informal gentlemen's agreement not to benefit electorally by pandering to this racist element. Peter Griffiths, the Conservative candidate in an election for the parliamentary seat of Smethwick, was accused of using the slogan 'If you want a nigger neighbour - vote Labour', in an attempt to capitalize on the electorate's fears of being 'swamped' by immigrants. He was said to have 'played the race card'.
The more recent meaning, which refers to someone attempting to gain advantage by drawing attention to their race, became commonplace in the USA around the time of O. J. Simpson's trial for the murder of Nicole Brown Simpson and Ronald Goldman. Several US newspapers used the phrase to describe the tactics of Simpson's defense lawyers; for example, this piece by Roger Simon in The Daily Herald, October 1995:
"Why was playing the race card necessary in order for O. J. Simpson to go free? Because it was the only way for the defense to deal with the massive physical evidence against him."