Ben Carson about to beat Trump.

War of Words Breaks Out Between Trump and Bush Over 9/11 

Real estate mogul Donald Trump remains the front-runner in the Republican presidential field, while former neurosurgeon Ben Carson holds a close second place, a new NBC News/Wall Street Journal poll shows.

With the backing of 25 percent of Republican primary voters, Trump is at his highest level of support in the poll since entering the 2016 race. Carson now gets the support of 22 percent of Republican voters, remaining within the margin of error of his first-place rival. Last month, 21 percent of GOP primary voters said Trump was their first choice for the party's nomination, while 20 percent picked Carson.

Carson's upside potential

While Trump leads when GOP primary voters are asked about their first choice for the party's nomination, Carson boasts the highest share of voters who say they can see themselves supporting him. Seventy-four percent said that they can imagine backing Carson for the GOP nod, while just 20 percent said they could not.

But Trump has also gained ground when it comes to whether or not potential voters can picture themselves backing him. Fifty-nine percent of GOP voters now say they can see themselves supporting Trump, while 36 percent disagree. Just last month, a slight majority — 52 percent — said they could not see themselves backing the real estate mogul, while 47 could envision it.

Rubio (65 percent could support/26 percent could not support) and Fiorina (56 could support/30 percent could not support) also show significant possible upsides among GOP voters.

The gap is narrower for Bush (51 percent could support/44 percent could not support) and Cruz (48 percent could support/41 percent could not support.)

When asked which candidate would be their second choice, GOP respondents tended to choose Carson, followed by Trump and Rubio. That tally means that, when GOP primary voters' first and second choices are combined, the former neurosurgeon manages to best Trump, 44 percent to 39 percent.

Carson runs strongest among very conservative Republicans, with 28 percent of that group's support, while Trump leads among those who say they are moderate or liberal (31 percent). Trump also leads among GOP primary voters who listen to talk radio (33 percent to Carson's 22 percent) and those who describe themselves as Tea Party supporters (28 percent to Carson's 22 percent).