In the survey — which contrasts sharply with other national polls — Cruz draws 28 percent, narrowly leading Trump at 26 percent. Trailing behind are Marco Rubio at 17 percent, John Kasich at 11 percent, Ben Carson at 10 percent and Jeb Bush at 4 percent.
The poll, taken after Trump's New Hampshire primary win and after a raucous GOP debate in which he bitterly criticized former President George W. Bush, diverged sharply from last month's NBC/WSJ survey in which Trump led Cruz by 33 percent to 20 percent. It also diverges from other recent national polls showing Trump maintaining a robust lead.
Republican pollster Bill McInturff, who conducts the NBC/WSJ poll with Democratic counterpart Peter Hart, cautioned that it's too early to say the results signal a definitive shift in the race.
"When you see a number this different, it means you might be right on top of a shift in the campaign," McInturff said. "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."
As for whether the survey shows Republicans pulling away from the billionaire businessman after his accusations that President Bush had lied before the Iraq War and failed to keep America safe, McInturff added, "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."
Republican strategists opposed to Trump have held out hope that a "ceiling" on his potential support might allow a rival to best him for the nomination once the Republican field thins. The NBC/WSJ poll provides some encouragement for them: just 56 percent of Republicans say they can envision supporting him, down from 65 percent in January. By contrast, 70 percent say they can envision supporting Rubio, and 65 percent say they can envision supporting Cruz.
If the race were narrowed to a two-candidate field, the poll shows, Cruz leads Trump by 56 percent to 40 percent, while Rubio leads by 57 percent to 41 percent.
Cruz is attempting to exploit a new issue — the fate of the Supreme Court vacancy left behind by the sudden passing of conservative Justice Antonin Scalia — to make gains in advance of this weekend's South Carolina Republican primary. The survey shows that 81 percent of Republicans want the Senate not to confirm a nominee to fill the vacancy from President Barack Obama. Cruz, a lawyer with extensive experience arguing before the court, has championed this view as have his GOP rivals.
At the same time, 81 percent of Democrats in the survey want the Senate to act on Obama's forthcoming nominees. As a result, the poll overall shows 43 percent say the Senate should vote this year on a replacement, while 42 percent prefer to leave the position vacant and vote next year on a replacement nominated by the new president. Fifteen percent have no opinion.
The telephone poll of 800 registered voters was conducted Feb. 14 to 16. It carries an overall margin of error of 3.5 percentage points.