A tiny rule tweak could significantly shake up next Republican debate

The criteria for the third Republican debate next month could lead to a shakeup in which candidates make the main stage.

CNBC, the host of the third GOP debate on October 28 in Boulder, Colorado, released its qualification criteria on Wednesday.

After speculation the network might axe the "undercard," lower-tier debate, CNBC announced the network would indeed host two debates.

The main, primetime debate will include candidates averaging at least 3% support in polls released between September 17 and October 21. (CNBC said candidates with an average of 2.5% would be rounded up to 3%.)

A separate, earlier debate would feature candidates who register at least 1% support in one major national poll during the same time period.

Though a small tweak, it could alter the debate landscape. Several candidates are teetering on the edge of qualification.

According to the current Real Clear Politics average, Sen. Rand Paul's (R-Kentucky) support has dropped below 3%, at 2.3%. By the same metric, New Jersey Gov. Chris Christie (R), at 3%, and former Arkansas Gov. Mike Huckabee, at 3%, both barely make the cut.

Some of the lower-polling candidates in recent days had pressed the Republican National Committee to not nix the "undercard" debate.

In a letter to RNC Chairman Reince Priebus obtained by Business Insider, Sen. Lindsey Graham's (R-South Carolina) campaign manager, Christian Ferry, urged the RNC to ask CNBC for a second debate, citing the fact that early polls are not always indicative of eventual nominees.

The lower-tier debate on CNBC will take place at 6 p.m. ET. The second, main-stage debate will follow at 8 p.m. ET, and the network said it would go on for two hours.

According to a CNBC press release, the contest will focus on "job growth, taxes, technology, retirement and the health of our national economy."