CBS News national poll!
Live-interview poll conducted 2/12 to 2/16. So 60% of this poll was conducted after the SC debate, which doesn’t appear to have hurt Trump.
Remember that Trump does worse on live-interview polls because some respondents (especially college-graduate respondents) don’t want to tell a live person that they support a politically incorrect candidate. But when people vote in the privacy of the voting booth, this isn’t a factor, so Trump will outperform live-interview polls in real secret-ballot primaries.
The NBC/WSJ poll showing different results than every other poll should be ignored as an outlier. That poll had a margin of error of 5%.