Mr. Assange has managed to wear out his welcome over the years, alienating many of his previous supporters, including Edward J. Snowden, the former American intelligence contractor who leaked documents about surveillance programs.
He also offended potential supporters in the Democratic Party by allowing WikiLeaks to become the conduit for emails hacked by Russia from the Democratic National Committee and leaked to harm the presidential candidacy of Hillary Clinton.
American intelligence agencies have concluded that Russian hackers working for the Kremlin carried out the intrusions, but Mr. Assange insists he did not know the source of the emails, under the working rules of WikiLeaks. He has denied working for Russia or any other government.
The United States attorney general, Jeff Sessions, has said that arresting Mr. Assange is a priority. “We have professionals that have been in the security business of the United States for many years that are shocked by the number of leaks, and some of them are quite serious,” he said last year.