The first GOP debate field is about to be set - and 2 big names are in danger of missing the main event

Fox Business Network is set to announce the field for the first Republican debate series of the year.

And it appears there will be a major shuffling of the lineup for Thursday's main event.

Following the network's decision last month to tighten debate qualification rules, it seems unlikely that former Hewlett-Packard CEO Carly Fiorina and Sen. Rand Paul (R-Kentucky) will qualify for the main debate stage.

Seven candidates appear likely to qualify for the main event, according to an analysis of recent surveys: Front-runner Donald Trump, Sen. Ted Cruz (R-Texas), Sen. Marco Rubio (R-Florida), retired neurosurgeon Ben Carson, New Jersey Gov. Chris Christie (R), former Florida Gov. Jeb Bush (R), Ohio Gov. John Kasich (R), and former Florida Gov. Jeb Bush (R).

That would constitute the smallest number of GOP candidates yet on the main stage. Paul, Fiorina, former Arkansas Gov. Mike Huckabee (R), and former Sen. Rick Santorum (R-Pennsylvania) would be relegated to the undercard event.

To qualify for the primetime debate stage, Fox Business requires candidates to place in the top five in either Iowa or New Hampshire based on an average of the five most-recent state polls recognized by the network. Or, candidates can place in the top six nationally. Candidates who do not make the main stage can qualify for the preceding "undercard" debate by registering at least 1% in at least one of the five most-recent national polls.

This leaves some ambiguity. In announcing its criteria last month, Fox Business did not specify which polls it plans to use to determine the debate field. (The network did not respond to a request for comment Monday.)

It said only that polls must be "conducted by major nationally and state recognized organizations that use standard methodological techniques (i.e., live interviewers, random digit-dial sampling techniques and include both landlines and cell phones)."

Among the most recent national polls of likely Republican primary voters that appear to meet Fox Business' qualifications - conducted by International Business Daily/TIPP, Fox News (two separate polls), CNN/ORC, and Quinnipiac University - Trump, Cruz, Rubio, Carson, Christie, and Bush would qualify. The same holds true in a scenario in which the network substitutes the earlier Fox News poll for an ABC/Washington Post poll.  

Kasich would grab the seventh spot because of his status in the top five in New Hampshire. The five most-recent polls of New Hampshire GOP voters were conducted by Monmouth University, NBC and the Wall Street Journal, Fox News, The Boston Herald, and the radio station WBUR. Averages of those polls, plus two other scenarios, leave Paul and Fiorina out.

And in Iowa, Fiorina and Paul are also on the outside looking in. The five most-recent polls of Iowa Republican caucus-goers - conducted by Quinnipiac University, NBC and the Wall Street Journal, Fox News, the Des Moines Register, and Gravis Marketing - put Trump, Cruz, Rubio, Carson, and Bush in the top five.

Even in the best scenario for Paul among recent polls of the Hawkeye state - if Fox Business uses an earlier Fox News polls instead of the Gravis poll -the senator still falls a point short of fifth place. The same holds true in scenarios in which the network substitutes the Gravis poll for December polls released by Loras College, Quinnipiac University, or Monmouth University.

On Monday, Paul's campaign said it hoped the senator would qualify for the main stage, based on the fact that he is in fifth in select early-state polls. 

"This race is hitting its final stretch and Rand Paul is a serious contender for the nomination," Doug Stafford, the Paul campaign's chief strategist, said in a statement. "He expects to be on the stage this week because he has qualified to do so and because he has a top tier campaign."

And Fiorina's deputy campaign manager noted on Twitter that Fox News' two most-recent national surveys have placed her in the top six: