I’ve Seen Civil War Destroy the Democrats Before. We Can’t Let it Happen Again.

I’ve lived through a Democratic Civil War before. In fact, I’ve been in the middle of two of them. The first was in 1968, when I was the research director for Vice President Hubert Humphrey’s presidential campaign. The second was in 1980, when I was Jimmy Carter’s policy director.

Both times, I watched pressure from the party’s liberal wing tear the party apart and bring down a Democratic presidential candidate. Both times, the Republicans took the White House. Both times, liberal dreams were shattered.

Today, I fear it could all...