The results from the poll — conducted after Trump's victory in New Hampshire and Saturday's GOP debate in South Carolina — are a significant reversal from last month, when Trump held a 13-point lead over Cruz, 33 percent to 20 percent.
Republican pollster Bill McInturff, who conducted this survey with Democratic pollster Peter Hart and his firm Hart Research Associates, says Trump's drop could signal being "right on top of a shift in the campaign."
"When you see a number this different, it means you might be right on top of a shift in the campaign. What you don't know yet is if the change is going to take place or if it is a momentary 'pause' before the numbers snap back into place," he said.
McInturff added, "So, one poll post-Saturday debate can only reflect there may have been a 'pause' as Republican voters take another look at Trump. This happened earlier this summer and he bounced back stronger. We will have to wait this time and see what voters decide."
This poll comes after other surveys -- both nationally and in South Carolina, the site of Saturday's next Republican contest -- show Trump with a commanding lead. But some of those weren't conducted entirely after the last debate like the NBC/WSJ poll.
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And in hypothetical one-on-one match ups, Trump trails both Cruz (56 percent to 40 percent) and Rubio (57 percent to 41 percent). In January, Trump was ahead of Rubio (by seven points) but behind Cruz (by eight points).
The NBC/WSJ poll was conducted Feb. 14-16 of 800 registered voters (which has a margin of error of plus-minus 3.5 percentage points) and 400 GOP primary voters (which has a margin of error of plus-minus 4.9 percentage points).
https://www.scribd.com/doc/299591277/NBC-WSJ-February-Poll-GOP?secret_password=JnP82QeNxD9kHWxwZuHr