"But the Democrats fumbled their advantage almost immediately. Rather than use their resources to cultivate local candidates and ideologically aligned intermediating organizations, the party chose to blast Obama supporters with emails and phone calls about the president's escalating war with Congress. Obama’s supporters checked out. The failure became crystal-clear in off-year elections, when Democrats struggled to generate support for down-ballot candidates. The party's inability in 2010 to elect Martha Coakley in Massachusetts, of all places, to replace the late Sen. Ted Kennedy, of all liberals, was a powerful lesson in the necessity of building an ecosystem of voters and organizations independent of rising star candidates."
Brent Cebul at The New Republic writes that "progressives must build up a range of intermediating organizations that can remake the Democratic Party from top to bottom and between presidential elections."
And Molly Ball at The Atlantic looks at various lessons for Democrats.