Donald Trump has jumped to the front of Republicans’ 2016 presidential candidate field nationally, holding that position even after a spate of incendiary comments by the real-estate magnate about Mexican migrants, other GOP candidates and party leaders, a Wall Street Journal/NBC News poll has found.

The poll, the latest of several national surveys to register the Trump surge, found that 19% of Republican primary voters picked Mr. Trump as their first choice for president, followed by 15% for Wisconsin Gov. Scott Walker and...