Ben Carson has edged ahead of Donald Trump nationally in the US battle for the Republican presidential nomination, according to a new poll.  The results mark the first time Trump has been dislodged from the top of the broad Republican field in months, and reflect continued preference for outsider candidates more than 13 months before the 2016 presidential election.  The New York Times/CBS News survey on Tuesday showed Carson, a retired pediatric neurosurgeon who has never held public office, was the presidential pick of 26 percent of respondents, compared with 22 percent for Trump, although the difference lay within the margin of error of six percentage points.  Other candidates trail far behind.  ANALYSIS: Ben Carson - The outsider who could beat Trump, and why he's even more unelectable  Senator Marco Rubio is third with eight per cent, while Jeb Bush, the former Florida governor and the son and brother of two presidents, is tied at seven per cent with former Hewlett-Packard chief executive Carly Fiorina.  Republican presidential hopeful Ben Carson. (AAP)  The survey does not herald drastic change, but it does suggest incremental shifts in a turbulent nomination process in which establishment-leaning candidates have struggled to make headway against strong populist currents in their party.  It comes the day before the next Republican primary debate, when a national audience will get another look at the top 10 candidates in the field.  Trump early on Tuesday retweeted a comment by a supporter saying there was too much emphasis on a single poll.  Trump has a point, said Nate Silver, a renowned statistician who closely follows elections.  "Disproportionate focus today on a poll that, for now, is an outlier by showing him behind Carson nationally," Silver said on Twitter.
In the latest sign of slippage for Donald Trump, a new poll shows Ben Carson has edged in front in the race for the Republican nomination.