Bill Mardo, a sportswriter for the Communist Party newspaper The Daily Worker who fought major league baseball’s color barrier in the 1940s when the mainstream American news media was largely silent on the subject, died Friday in Manhattan. He was 88.

The cause was complications of Parkinson’s disease, his companion, Ruth Ost, said.

In the years before the Brooklyn Dodgers signed Jackie Robinson as the first black player in modern organized baseball, Mr. Mardo was a leading voice in a campaign by The Daily Worker against racism in the game, a battle it had begun in 1936 when Lester Rodney became its first sports editor.

Mr. Mardo, who joined The Daily Worker in 1942, oversaw its sports coverage, together with Nat Low, during World War II, when Mr. Rodney was in the Army. Mr. Mardo had a deferment, having lost vision in one eye from a childhood virus.

The Daily Worker asked fans to write to the New York City baseball teams urging them to sign Negro league players at a time when the major leagues had lost much of their talent to military service. A milestone in baseball history and the civil rights movement arrived in October 1945 when Robinson signed a contract with the Dodgers’ organization, having reached an agreement with Branch Rickey, the Dodger general manager, two months earlier.