Previous polls had showed that Trump would do far worse against Clinton than the other Republican candidates. Those polls showed that Trump would get clobbered by Clinton in the general election. The newest poll says that it would be very close between Hillary and Trump, with Clinton leading Trump by just 2 percentage points. In addition, it shows that Cruz would not do as well against Clinton as Trump. This is surprising since previous polls showed just the opposite.
http://www.nbcnews.com/politics/2016...atchup-n554306