Feinstein was set to lead her state's delegation at the event.
AP has the details:
WASHINGTON (AP) - Democratic Sen. Dianne Feinstein of California has broken her ankle and will miss next week's Democratic National Convention. Feinstein, who was one of Hillary Rodham Clinton's top supporters, was to have chaired California's delegation to the convention in Denver.
Feinstein slipped and broke her ankle on Friday while talking a walk in the Tahoe forest in California with Rep. Ellen Tauscher (D-Calif.) the senator said in a statement Tuesday.
Feinstein was at Lake Tahoe for a gathering of elected officials called the Lake Tahoe Summit.
She said her doctor has advised her not to travel.