For the first time in months, Donald Trump is not leading the latest national poll of Republican primary voters. CBS News released their latest polling today which finds Ben Carson leading the race followed closely by Donald Trump. Of course, this is only one poll, but it comes on the eve of the next Republican debate so there will be a lot hinging on the performance of Carson and whether he can build on momentum or get knocked off by Trump.

Report from CBS News:

Ben Carson has surpassed Donald Trump and now narrowly leads the Republican field in the race for the nomination in the latest national CBS News/New York Times Poll.

Twenty-six percent of Republican primary voters back Carson, giving him a four-point edge over Trump (22 percent). Support for Carson has quadrupled since August.

The rest of the Republican presidential candidates lag far behind in single digits. Marco Rubio is now in third place (eight percent), followed by Jeb Bush (seven percent) and Carly Fiorina (seven percent). All other candidates are at four percent or lower.

The full breakdown:

26% – Carson
22% – Trump
8% – Rubio
7% – Bush, Fiorina (tied)
4% or less everyone else

There is no question this will become a topic at the CNBC Republican Debate tomorrow night. How will Trump handle himself when running behind (if you believe the polling), compared to running the table in every poll? Trump has already taken a few shots at Carson’s religious affiliation, raising questions about the beliefs of the Seventh Day Adventist church.

This could be an outlier, but it would pickup the trend happening in Iowa where Carson has taken the lead in three separate polls. We’ll see tomorrow night when the candidates take the stage at 8pm ET (5pm PT) on CNBC.