Just seven candidates will take the main stage for the next Republican presidential debate, on the Fox Business Network Thursday evening — the fewest of any GOP debate so far in the 2016 campaign.

Businessman Donald Trump, Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, Dr. Ben Carson, New Jersey Gov. Chris Christie, former Florida Gov. Jeb Bush and Ohio Gov. John Kasich will battle it out in the main event in Charleston, S.C.

Kentucky Sen. Rand Paul and former Hewlett-Packard CEO Carly Fiorina did not make the cut for the main debate and have been assigned to an earlier matchup with former Arkansas Gov. Mike Huckabee and former Pennsylvania Sen. Rick Santorum.

But Paul won’t be there.

“We will not participate in anything that is not first-tier,” Paul told CNN shortly after the announcement.

Paul’s campaign has been criticizing the debate criteria for days, repeating widely held criticism that the TV networks hosting primary debates are basing their selection on polling.

They had warned that Paul would not show up for an “undercard” matchup.

“By any reasonable criteria Senator Paul has a top tier campaign,” a statement from the Paul campaign said just after the lineup was announced Monday evening. “He will not let the media decide the tiers of this race and will instead take his message directly to the voters of New Hampshire and Iowa.”

The top-tier debate, with just seven participants, will be the smallest yet this campaign season. At one point, 11 candidates were on the main stage.

The criteria to make the main debate were set out by Fox last month. A candidate had to average in the top six slots nationally, or in the top five in Iowa or New Hampshire in a set of recent polls selected by the network.

Previous debates were selected based on national polling.

Recent polling suggests that including the Iowa and New Hampshire polls helped Kasich make the cut, as he is performing much better in New Hampshire than he is nationally.

In fact, the latest average of polls from Real Clear Politics shows Kasich behind Paul and Fiorina nationally. But national polls are a problematic measure in a primary since the contests are won state by state over a period of months.

The first contest of the 2016 presidential campaign — the Iowa caucuses — will be held on Feb. 1.

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