According to polling rules set forth by the FOX Business Network, the next Republican debate in January may reduce the number of candidates on stage by three.

Ben Kamisar reports at The Hill:

Next GOP debate stage could shrink to six candidates

As few as six candidates could make the next GOP presidential debate stage in January, as Fox Business Network’s new criteria could drastically shrink the field less than a month before the Iowa caucuses.

Fox Business Network announced three separate avenues to make the main stage, but those pathways are more restricted than in previous debates. Participants in the main stage debate on Jan. 14 must hit the top six in an average of five recent national polls, or top five in an average of recent polls from Iowa or New Hampshire…

Fox Business Network, as in the past, hasn’t announced which polls it would use. But using current RealClearPolitics averages, Donald Trump, Sen. Ted Cruz (Texas), Sen. Marco Rubio (Fla.), Ben Carson, former Gov. Jeb Bush (Fla.), and Gov. Chris Christie (N.J.) currently sit in the national top six…

That would relegate Sen. Rand Paul (Ky.), Carly FIorina, and Gov. John Kasich (Ohio) to the undercard debate weeks before the first votes of 2016 are cast.

If that happens, Rand will refuse to participate in undercard:

It’s surprising that Jeb Bush will likely make the cut given his poor poll numbers.

Hadas Gold of Politico has more:

Only six GOP candidates likely to make next debate stage

According to polling released as of Tuesday, the undercard debate stage would include Sen. Paul, Gov. Kasich, Fiorina, former Gov. Mike Huckabee, former Sen. Rick Santorum and former Gov. George Pataki.

The networks are still struggling to accommodate the unwieldy GOP field, which has been winnowed to 13 but still represents a sprawling contest. Controversy has swirled around the lineup for multiple debates, with criteria changing twice to get Fiorina bumped up to the main event during the second debate and Paul clinging to the prime-time stage of the most recent GOP debate despite technically not having the right numbers.

The debate will air on the FOX Business Network on Thursday, January 14th.