Oscar Lopez Rivera, a Puerto Rican independence activist convicted 35 years ago of a conspiracy against the U.S. government, will be freed from prison after President Obama commuted his sentence. Although lower-profile than the pardon of Chelsea Manning, the U.S. soldier convicted of giving classified information to WikiLeaks, the Rivera pardon has another distinction — it was personally campaigned for by Sen. Bernie Sanders (I-Vt.).

In May 2016, before the Democratic primary in Puerto Rico, Sanders drew attention to Lopez Rivera’s imprisonment. It didn’t rise to great prominence as an issue, and Hillary Clinton easily won the primary.

But from that point, Sanders was invested in the cause that had also attracted the support of Archbishop Desmond Tutu and “Hamilton” songwriter Lin-Manuel Miranda. In October, Sanders recorded a video with his campaign group, Our Revolution, telling the president that “all over the world, in the United States and in Puerto Rico, thousands and thousands of people are demanding that” the “Vietnam War hero” Lopez Rivera be released from jail.

The cause remained somewhat obscure and politically fraught. Lopez Rivera had won a Bronze Star in Vietnam; after that, however, he had joined the Fuerzas Armadas de Liberación Nacional (FALN), a terrorist organization that killed and wounded people with bomb attacks that Lopez Rivera was linked to. In 1999, when President Bill Clinton offered to commute the sentences of most FALN members, Lopez Rivera refused the terms of the deal.

But after the 2016 election, with Clinton’s defeat lowering the political stakes of Obama’s pardons, Sanders kept up the pressure. Our Revolution kept asking members to call and lobby for a pardon.

Sanders, whose membership on the Senate’s Energy and Natural Resources Committee kept him tied up Tuesday, eventually responded on Twitter.