Those numbers represent a dramatic turnaround from the November poll, in which Carson led the Republican field in with 22 percent, while Trump and Rubio each had19 percent of voters' support. He's followed by Marco Rubio, Ted Cruz and Ben Carson.
Republican primary voters were asked who they thought was most likely to win the GOP presidential nomination and 49% said Trump.
Trump was tied for second last time with 19 percent.
"Support for Sanders has come from those who are new to the process, but the current poll indicates he is also cutting into Clinton's lead among die-hard Democratic partisans", said Monmouth polling director Patrick Murray. All other Republican candidates get just two percent backing apiece from likely caucus-goers. Only 30 per cent said Trump, who identifies as a Presbyterian, is religious enough (25 per cent) or "very" religious (five per cent.) Among Republicans, 47 per cent said they don't regard Trump as religious.
Of the candidates tested, only Sanders comes out ahead in terms of comfort vs. anxiety: Fifty percent of Americans are comfortable with the idea of a Sanders presidency vs. 43 percent who are anxious about it. Americans are more nervous than calm about Cruz (-8 points), and slightly more concerned about Rubio and Clinton (both -5).
According to recent media reports, he would be especially interested in running if Trump and Sanders win their party nominations, and would spend at least $1 billion of his own money to drive his campaign.
On the Democratic side former Secretary of State Hillary Clinton is at 61 percent with a big lead over Sen.
Almost 49 percent of Republicans think Trump will win, and more than 65 percent of Democrats believe Clinton will be the party's nominee.
Sanders beats out the GOP contenders among Wisconsin voters by two-digit margins.
Were such a scenario to break, there's "a real possibility" Rubio could capture 20 to 25 percent, PPP states.
The poll of 600 registered Tennessee voters was conducted January 15-20 and has a margin of error of 4 percentage points.
The survey was done from Jan 7-14 based on answers from 2,009 adults. The New York billionaire developer's 16 percentage point-lead is on par in several S.C. polls taken over the past month.
Seven percent of likely voters in the S.C. Democratic primary did not choose a favorite.