Poll: Trump leads Cruz by 18 points nationwide
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Donald TrumpDonald John TrumpDems flip Wisconsin state Senate seat Sessions: 'We should be like Canada' in how we take in immigrants GOP rep: 'Sheet metal and garbage' everywhere in Haiti MORE leads Sen. Ted CruzRafael (Ted) Edward CruzWith religious liberty memo, Trump made America free to be faithful again Interstate compacts aren't the right way to fix occupational licensing laws Texas Dem: ‘I don’t know what to believe’ about what Trump wants for wall MORE (R-Texas) by double digits in the race for the GOP’s 2016 presidential nomination nationwide, according to a new poll.

Trump has a nearly 20-point edge over Cruz in the latest NBC News/Survey Monkey poll, which comes less than three weeks before Iowa's first-in-the-nation caucuses.

The outspoken billionaire remains the front-runner for the Republican nomination, with 38 percent, pollsters said. Cruz is second, with 20 percent, while Sen. Marco Rubio (R-Fla.) takes third, with 11 percent.

No other Republican White House hopeful registers double-digit support in Tuesday’s results. Retired neurosurgeon Ben Carson is fourth with 9 percent.

Former Gov. Jeb Bush (R-Fla.), Gov. Chris Christie (R-N.J.) and Sen. Rand Paul (R-Ky.) are deadlocked in fifth place, with 3 percent apiece.

About 5 percent do not know yet who they are voting for in the GOP’s 2016 presidential primary. Another 1 percent have no answer.

Tuesday’s results also show that voters are generally decisive about their top candidate heading toward Iowa.

Approximately 40 percent said they are “absolutely certain” who they will in 2016. An additional 39 percent said there is a “large chance” they will stick with their current choice.

Roughly 18 percent are 50-50 on their candidate, while 2 percent say there is a “small chance” they will stick with their contender.

NBC News and Survey Monkey polled 2,852 registered Republican voters Jan. 4–10. The findings, released early Tuesday, have a 2.4 percent margin of error.