I'm a Democratic strategist with an urgent warning for my fellow Dems

More than a decade ago, in 2014, Republican House Majority Leader Eric Cantor suffered one of the most shocking primary defeats in modern political history. He lost to Dave Brat, by all accounts an underdog tea party member, lacking in Cantor’s name recognition and fundraising bona fides, but who was further to the right on political ideology and had grassroots support. The warning signs were there, but Cantor and the Republican establishment ignored them, convinced their power and money could outmatch an insurgent wave.