The cast of this Thursday's primetime Republican debate will be the smallest yet. Fox Business has announced that two mainstays of the primetime debate — Rand Paul and Carly Fiorina — have failed to meet the network's new tougher polling requirements for inclusion.

What Fox changed this time around was that it limited the primetime debate to the top six candidates in either national, Iowa, or New Hampshire polls (rather than saying that candidates needed to get a certain amount of support in the polls). Here's who made the cut:

The candidate lineup for the @FoxBusiness 9p ET #GOPDebate on Thursday, January 14th: pic.twitter.com/P0OH4ik4dW — FOX Business (@FoxBusiness) January 12, 2016

The top six nationally are Donald Trump, Ted Cruz, Marco Rubio, Ben Carson, Chris Christie, and Jeb Bush. In addition, John Kasich is currently polling third in New Hampshire, so he's allowed in too. (Rand Paul very narrowly failed to qualify — he's polling in seventh in Iowa.)

Theoretically, that leaves these four remaining candidates for the "undercard" segment, which is aired earlier in the evening:

The candidate lineup for the @FoxBusiness 6p ET #GOPDebate on Thursday, January 14th: pic.twitter.com/XAcdE01R8X — FOX Business (@FoxBusiness) January 12, 2016

However, Rand Paul has repeatedly said that he would not participate in the debate at all if he was demoted to the undercard segment, and he confirmed as much to the Washington Post's David Weigel Monday night.