Donald Trump opens 21-point lead over Ted Cruz as others trail, poll finds
Donald Trump appears at a fundraiser held onboard the USS Iowa. [MSNBC]

Donald Trump has pulled further ahead of his rivals for the Republican presidential nomination, as he heads towards 2016 with a 21-point lead, according to a new CNN poll.

Ted Cruz has also surged into a clear second place, leaving others trailing far behind.

Since the last Republican debate of the year last week, and his comments that Muslims should be banned from entering the US, Trump has become more popular.

The New York real estate mogul has topped the latest poll with 39% support from registered GOP voters and Republican-leaning independents, an analysis on Wednesday morning from CNN/ORC revealed .

That’s twice as much support as his closest rival, Ted Cruz, who has nevertheless risen two points since the last poll to reach 18% – 21 points behind Trump.

Related: New Hampshire primary: Republican establishment races to topple Trump

In the previous CNN/ORC survey taken in late November, Trump was at 36% and, on the far horizon, three others were bunched fairly closely together to make a small but important second-placed pack: Cruz with 16%, Ben Carson with 14% and Marco Rubio with 12%. All of the other contenders were polling below 5%.

In the latest poll, Carson and Rubio have slid, both standing at 10% behind Cruz’s 18%. The next contender is New Jersey governor Chris Christie, at 5%, followed by Rand Paul at four and Jeb Bush at three.

Trump has been unassailably on top of the polls since he first took the lead in July.

With less than six weeks to go until the first official nominating contests begin with the Iowa caucus, followed swiftly by the crucial opening primary in New Hampshire, the more establishment Republican candidates are criss-crossing the New England state in an effort to crack Trump’s lead.

In the CNN poll, 46% of GOP voters say the Republicans have a better chance of winning the White House in 2016 with Trump as their nominee; but a greater percentage of those polled think another candidate would clinch the nomination.

The remaining problem for Trump’s rivals is that voters are split on who that should be.

Cruz has bolstered his strength in the runner-up position. A quarter said they would support the Texas senator if they chose someone other than Trump, followed by Rubio at 16% and Carson at 13%.

When respondents were asked who had the right experience to be president, Wednesday’s poll found Cruz leapfrogged Trump and was by far the favorite with 62%, ahead of Trump’s 57% and third-placed Rubio at 53%.

Significantly for the national race, a Quinnipiac poll on Tuesday found that half of US voters say they would be embarrassed if Trump were voted president. © Guardian News and Media 2015