When Steve Cobble unexpectedly passed away last week at the age of 69, we lost a giant and a dearly beloved brother. Cobble devoted his life to engaging the civilizing movements of our time with electoral politics. He combined qualities seldom seen together. He was brilliant and modest, strategic and generous, analytical and funny. He was a gifted political organizer, quiet leader, and creative visionary. He had both a radical will and a gentle soul.

I first met Cobble when Joe Johnson brought him into our 1984 presidential campaign. Cobble immediately helped pull together the campaign, took charge of the critical effort to identify and win delegates, and mastered the maze that is the Democratic Party’s rule book. He became the architect of hope, helping to win proportional representation rather than winner-take-all in primaries—a reform critical to insurgent candidacies from Jackson ’88 to Barack Obama and Bernie Sanders.

Cobble’s passion was peace. He first came into presidential politics when he was 20, living in a small town in New Mexico, a self-described long-haired anti-war hippy. When the 1972 George McGovern campaign was desperate for a county organizer, Cobble volunteered, and, to his own amazement, helped McGovern win the county and the state in the Democratic primaries. He went on to help elect the most progressive governor in New Mexico history, Tony Anaya.

After my 1988 campaign, Cobble served as political director of the Rainbow Push Coalition and remained my personal adviser and strategist. He traveled with me, drafted speeches, and produced legions of memos. Cobble also served as political director for the successful campaign of Carol Mosely Braun, the first African American woman elected to the US Senate. Cobble cofounded Progressive Democrats of America to help lead the charge against this country’s endless wars. Under his leadership, PDA led the first “draft Bernie effort,” and was the first national organization to endorse Sanders in 2016.

Representative Jamie Raskin, the former counsel to the Rainbow Push Coalition, described Cobble as “a hardcore practitioner of grassroots electoral politics who urged progressives not just to dream big but to organize seriously and systematically in order to win. He helped me in every campaign I ever ran, and I will miss him sharply.”

Cobble also served as director of the Arca Foundation, which made pathbreaking donations for cutting-edge progressive causes. He was an associate fellow at the Institute for Policy Studies and the Kennedy School at Harvard. At IPS, he contributed to its seminal 2007 report “Just Security: An Alternative Foreign Policy Framework.”

Through all this, Cobble was truly devoted to his family, his beloved Molly and his daughters, Liz and Julie, and his grandchildren. In recent years, he had moved to Texas to be near to Molly’s parents and his grandchildren.

Cobble will be missed, and he will be remembered. I personally will miss his strategic advice, his quiet humor, and his fierce commitment to peace and justice.