Greg Sargent: Three big takeaways from Trump's humiliating Pennsylvania failure

Democrat Conor Lamb is clinging to a lead of around 600 votes in Pennsylvania’s 18th Congressional District, but most news organizations have refrained from calling the race. Still, it looks likely Lamb will hang on, and win or lose, we now know that this district — which President Donald Trump won by 20 points — swung in a huge way toward Democrats, making this a major rebuke of Trump and Republicans, deep in the heart of Trump country.Three key takeaways:• The House map