Trump takes 17-point lead in national poll
All other candidates are in single digits in the survey, which comes just weeks before ballots are cast in the early-voting states of Iowa and New Hampshire, which have shown tighter races.
Trump lead over Cruz is 2 points slimmer than last month’s version of the same poll.
Trump has spent two weeks questioning whether Cruz, who was born in Canada to an American mother, is eligible to be president. Cruz has insisted he is eligible and pushed back on Trump.
A majority of Trump supporters in the latest national poll, 52 percent, say that their mind is made up, while 47 percent say it's too early to say who they will support.
The survey of 442 GOP primary voters was conducted Jan. 7-10 with a margin of error of 6 points.