Paris was the first stop for Soros on a monthlong spring trip to Europe. He normally would have visited Budapest, but not this time. Hungary’s prime minister, Viktor Orban, a former Soros protégé, was re-elected in April after running a campaign in which he effectively made Soros his opponent. Orban accused Soros, who is an American citizen, of plotting to overwhelm Hungary with Muslim immigrants in order to undermine its Christian heritage. He attacked Soros during campaign rallies, and his government plastered the country with anti-Soros billboards. In the aftermath of the election, the O.S.F. announced that it was closing its Budapest office because of concerns for the safety of its employees. The fate of the Soros-founded Central European University, based in Budapest, was also in doubt.

Soros said he couldn’t visit Hungary under present circumstances: “It would be toxic,” he said. He told me that Orban’s campaign was “a big disappointment,” but quickly added, “I think I must be doing something right to look at who my enemies are.” Last autumn, he signaled that same sense of defiance when he announced that he was in the process of transferring the bulk of his remaining wealth, $18 billion in total at the time, to the O.S.F. That will potentially make it the second-largest philanthropic organization in the United States, in assets, after the Bill & Melinda Gates Foundation. It is already a sprawling entity, with some 1,800 employees in 35 countries, a global advisory board, eight regional boards and 17 issue-oriented boards. Its annual budget of around $1 billion finances projects in education, public health, independent media, immigration and criminal-justice reform and other areas. Organizations like Human Rights Watch, Amnesty International, the American Civil Liberties Union and Planned Parenthood are among its grantees.