Maybe GOP voters simply agree with Trump? 2010 poll found 63% of Rs oppose birthright citizenship: http://t.co/Y1W1mECwx3

— Greg Sargent (@ThePlumLineGS) August 19, 2015

Trump isn’t plucking this crazy out of the ether. He’s mining the rich layer of bovine excrement laid down by his predecessors and has found fertile ground.