Trump now up 21 points over closest competitor, Cruz
© Greg Nash

Republican candidate Donald TrumpDonald John TrumpKoch-backed group launches six-figure ad buy against Heitkamp Anti-abortion Dem wins primary fight Lipinski holds slim lead in tough Illinois primary fight MORE added 3 points in a new CNN/ORC International poll released early Wednesday to expand his commanding lead over the GOP presidential field.

Trump now has the support of 39 percent of Republicans independents who lean Republicans.

Sen. Ted CruzRafael (Ted) Edward CruzCruz says Cambridge Analytica assured him its practices were legal Dem battling Cruz in Texas: ‘I can understand how people think this is crazy’ Overnight Tech: Facebook faces crisis over Cambridge Analytica data | Lawmakers demand answers | What to watch for next | Day one of AT&T's merger trial | Self-driving Uber car kills pedestrian MORE (R-Texas) strengthened his second-place standing, adding 2 points since a similar poll in early December. He currently has 18 percent support.

Ben CarsonBenjamin (Ben) Solomon CarsonBen Carson suggests wife made decision to purchase ,000 dining set The Hill's 12:30 Report Cost of Pruitt's Italy trip rises above ,000 MORE and Sen. Marco RubioMarco Antonio RubioRubio: McCabe 'should've been allowed to finish through the weekend' For Tillerson, bucking Trump became a job-killer At least six dead after pedestrian bridge collapses on cars in Florida MORE (R-Fla.), who both saw their support fall in the new national poll, are tied for third, with 10 percent apiece.

No other GOP contender had more than 5 percent support.

Trump is widely seen as the candidate most capable of handling the major issues facing the nation today.

A strong majority, 57 percent, said the billionaire businessman would be the best Republican primary contender to deal with the economy. His closest competitors are Cruz at 8 percent and Rubio at 7 percent.

Fifty-five percent also said they trust Trump most on illegal immigration, followed by Cruz at 15 percent and Rubio at 10 percent.

And despite never holding elected office, 47 percent said Trump would be preferred as commander in chief in the ongoing fight against the Islamic State in Iraq and Syria (ISIS).

The poll also found that Trump's support is largely comprised of non-college-educated voters. Among those without a degree, 46 percent back Trump, while only 27 percent of graduates said they support his candidacy.

The poll of 1,018 adults was conducted Dec. 17 to Dec. 21, following the last GOP debate on Dec. 15 in Las Vegas. It has a margin of error of 3 percentage points.

--Bradford Richardson contributed to this report, which was updated at 7:48 a.m.