The group-think of journalists covering elections and a couple of victories they missed

For political journalists, writes Walter Shapiro on the US Brookings website, there is safety in a system that places inordinate emphasis on objective measures like polls and campaign coffers.

Before the votes are tallied, everything else in campaign stories is subjective. Experienced reporters make arbitrary decisions on who to quote, which anecdotes are relevant, and the “underlying mood of the electorate.” Sometimes their instincts are right, sometimes they become overly wedded to an existing storyline like Hillary Clinton’s inevitability.
At a moment when all reporters worry about accusations of bias, it is comforting to say their candidate assessments are based on tangible numbers from polls and fund-raising tallies. This invariably leads to group-think campaign coverage in which only the most iconoclastic reporters are willing to challenge the conventional wisdom about who will win.

Sometimes the herd gets it wrong when unexpected candidates run campaigns that go viral and the media ends up surprised.
That's what happened recently in a couple of Democratic primaries and the You Tube videos show why two political unknowns defeated well established incumbents.
In New York Alexandria Ocasio-Cortez's “The Courage to Change” narrates a capsule history of her life, recounting how she was born in the Bronx, worked as an educator, organiser and waitress and became a candidate because “every day gets harder for working families like mine to get by.”

MJ Hegar, running in Texas, describes how "my whole life has been about opening, pushing, and sometimes kicking through every door in my way. Ready for a Congress that opens doors for Americans instead of slamming them in our faces? "