Steinberg, 59, died Friday in New York after a brief struggle with cancer, said Menachem Rosensaft, a vice president of the American Gathering of Jewish Holocaust Survivors and Their Descendants. Steinberg was also a vice president of the organization.
After joining the World Jewish Congress in 1978 as its United Nations representative, Steinberg quickly rose to become its executive director, key spokesman and primary behind-the-scenes strategist.
He achieved what was arguably his greatest triumph in the late 1990s, when a campaign he orchestrated against Swiss banks resulted in more than $1 billion in compensation for victims of the Holocaust and their descendants.
"There is no denying that the Swiss were the bankers and launderers for Hitler's Germany," Steinberg told The Times in 1997.
When Waldheim was running for president of Austria in 1986, Steinberg and the World Jewish Congress challenged his denials of a Nazi past by releasing documents that linked the diplomat to World War II atrocities.
"We don't know if he committed a war crime, but he was in places where god-awful things happened," Steinberg said at a 1986 news conference.
Waldheim won the presidency but less than a year later, the U.S. government banned him from entering the country, saying that evidence showed he had persecuted Jews, Allied prisoners and others. The ban remained in place until Waldheim's death in 2007.
Steinberg's ability to eloquently frame a controversy was evident in 1998, when Jewish groups sought restitution for art and property that had been looted by Nazi Germany. He called the missing possessions "the last prisoners of war."
During the Holocaust, his Polish-born parents, Max and Rose Steinberg, hid in the underground bunker of a Polish farm family before making their way to a ship bound for Israel, where Elan Steinberg was born in June 1952.
The family eventually moved to New York, where Steinberg grew up hearing "the stories of how everything in Europe had been destroyed or stolen, and how everyone had been murdered," according to the 2001 book "Pack of Thieves."
He earned a degree from Brooklyn College and a master's degree from City University of New York, where he taught.
Steinberg resigned from the World Jewish Congress in 2004 but later returned as a consultant. At the American Gathering of Jewish Holocaust Survivors and Their Descendants, Steinberg served as a spokesman for survivor communities.
"He dedicated himself throughout his life to Holocaust remembrance and to ensuring that those who profiteered from the Holocaust would not get away with it," Rosensaft said. "He was a person of literally the highest integrity who was also extremely unafraid to confront those whom others were afraid of."
Steinberg is survived by his wife, Sharon; children Max, Harry and Lena; and brother, Alex.