Low-polling Republican presidential hopefuls like Rand Paul and Chris Christie will need to clear a higher bar in order to make the main stage at next month's GOP primary debate.

CNBC announced Wednesday that candidates must have an average of at least 3% among recognized national polls in order to participate in their primetime debate on Oct. 28. Candidates who can't clear 3% will be relegated to the undercard debate.

That is a departure from the first two Republican contests, which took the top 10 or 11 candidates for the main stage based on an average of national polls, including some candidates who had less than 3% support.

It's not clear how many candidates would clear the 3% mark, but it is expected to put Paul, Christie and Mike Huckabee at risk of being relegated to the undercard. All three of those candidates are currently hovering around the 3% mark in an average of recent national polls.

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The fact that CNBC is even holding an undercard debate is surprising, given that Republican National Committee officials have said privately that the Sept. 16 debate would be the last to feature two rounds.

In a statement, RNC Chairman Reince Priebus said the committee applauded "CNBC's efforts to ensure that all of our top candidates will have an opportunity to share their views with the American people."

The nationally recognized polls for the CNBC debate are those from NBC, ABC, CBS, Fox, CNN and Bloomberg released between September 17 and October 21.

CNBC also announced that the moderators for the Oct. 28 debate will be Carl Quintanilla, co-anchor of "Squawk on the Street" and "Squawk Alley"; Becky Quick, co-anchor of "Squawk Box;" and chief Washington correspondent John Harwood. They will be joined by On-Air Editor Rick Santelli, Senior Personal Finance Correspondent Sharon Epperson and "Mad Money" host Jim Cramer, meaning a total of six questioners will appear on stage.

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The debate will be held at the Coors Events Center at the University of Colorado Boulder and broadcast live on CNBC. It is being branded as the "Your Money, Your Vote" debate, and will focus on the economy, job growth, taxes, technology, retirement and the health of our national economy.

"We focus on money -- from financial markets and economies around the world to the most fundamental pocketbook issues involving savings and retirement," Mark Hoffman, the chairman of CNBC, said in a statement. "Financial freedom, entrepreneurship and job growth are core to Americans' decision making process when they cast their vote."

"Squawk Box" co-anchor Joe Kernen and "Closing Bell" co-anchor Kelly Evans will host special programming leading up to the debate.

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