On the eve of the next Republican debate, in Colorado Oct. 28, a new CBS/New York Times poll shows that Ben Carson has edged ahead of Donald Trump in the race for the GOP nomination, though the gap remains within the poll's margin of error.

Just over a quarter -- 26% -- of Republican primary voters now support Carson compared with 22% for Trump, followed by Marco Rubio in third place at 8%, and Jeb Bush and Carly Fiorina each with 7%, according to the poll.

The margin of error is 4 percentage points plus or minus for the whole sample, and 6 percentage points for Republican voters, which means that Carson and Trump are in a statistical dead heat.

But the poll also found that a majority of Republican voters (7 of 10) say they are not sure about who they will support.

The poll was a random telephone surveyof 1,289 adults nationwide conducted Oct. 21-25.