Poll: Trump holds 17-point lead
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Donald TrumpDonald John TrumpHouse Democrat slams Donald Trump Jr. for ‘serious case of amnesia’ after testimony Skier Lindsey Vonn: I don’t want to represent Trump at Olympics Poll: 4 in 10 Republicans think senior Trump advisers had improper dealings with Russia MORE continues to hold a big lead in the race for the 2016 Republican presidential nomination, leading his closest rivals by double digits in an NBC News/Survey Monkey poll released Tuesday.

The billionaire businessman is supported by 35 percent of Republican and GOP-leaning registered voters in the online survey, with Sens. Ted CruzRafael (Ted) Edward CruzDebbie Wasserman Schultz marks 10 years as breast cancer survivor Foreign agent registration is no magical shield against Russian propaganda Let Trump be Trump and he'll sail through 2020 MORE (Texas) and Marco RubioMarco Antonio RubioRyan pledges 'entitlement reform' in 2018 Richard Gere welcomes lawmakers' words of support for Tibet Dem lawmaker gives McConnell's tax reform op-ed a failing grade MORE (Fla.) at 18 percent and 13 percent, respectively.

All other candidates poll in single digits, with retired neurosurgeon Ben Carson at 9 percent, former Florida Gov. Jeb Bush at 6 percent, New Jersey Gov. Chris Christie at 4 percent and businesswoman Carly Fiorina at 3 percent.

A third of white evangelicals surveyed, 33 percent, support Trump, while Cruz gets 21 percent and Rubio 10 percent of that group, a key support group candidates are focusing on in the early voting state of Iowa.

Trump is also supported by 35 percent of "very conservative" voters, versus 30 percent for Cruz and 8 percent for Rubio.

The poll comes about a month out from votes being cast in the race in the Iowa causes Feb. 1, where Cruz is the favorite to win, and the New Hampshire primaries Feb. 9, where Cruz and Rubio poll behind Trump.

Cruz and Rubio have largely avoided attacking Trump and have focused their barbs on each other recently, duking it out on the issue of national security and immigration heading into the next debates later this month.

On the Democratic side of the field, Hillary ClintonHillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE leads Sen. Bernie SandersBernard (Bernie) SandersSchumer: Franken should resign Franken resignation could upend Minnesota races Avalanche of Democratic senators say Franken should resign MORE (I-Vt.) 53 percent to 36 percent, with just 2 percent of registered and leaning Democrats supporting former Maryland Gov. Martin O'Malley.

The survey of 3,700 adults nationally was conducted Dec. 28 through Jan. 3 with an overall margin of error of 1.9 points. The margin of error for the 949 GOP registered voters surveyed is 3.7 points and 3.3 points for the Democrats.