Rand Paul
Republican presidential candidate Rand Paul has announced his intention to boycott the next GOP debate.Getty Images

Rand Paul has said he would boycott the Republican presidential debate after the GOP contender did not qualify for the main event.

His announcement came only minutes after the seven candidates who had qualified for the main debate on 14 January had been announced, with Paul among four relegated to the earlier undercard debate.

Republican presidential frontrunner Donald Trump will be joined by Texas Senator Ted Cruz, Florida Senator Marco Rubio, New Jersey Governor Chris Christie, Ohio Governor John Kasich, retired neurosurgeon Ben Carson and former Florida Governor Jeb Bush for the main debate which will be broadcast live at 9pm EST/2am GMT.

Paul—who has already said he would not participate—was part of the undercard debate airing at 6pm EST/11pm. Former Pennsylvania Senator Rick Santorum, former Arkansas Governor Mike Huckabee and former businesswoman Carly Fiorina will participate in the earlier debate. Paul's campaign made the decision to boycott the debate shortly after the lineup was announced.

"By any reasonable criteria Senator Paul has a top-tier campaign," the Kentucky senator's campaign said. "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." It was the first time Paul has not qualified for the prime-time debate, Fox News reported.

Paul told The Washington Post that he believed they had "made a mistake", adding: "I'm not willing to accept a designation as a minor campaign. We've raised $25M (£17m). We've gotten on the ballot on every state. It's kind of ridiculous to arbitrarily rate the campaigns based on national polling."

According to Fox News, the debate line-up is based on the results of national, New Hampshire and Iowa polls. Candidates had to place in the top six in an average of recent national polls or in the top five in an average of recent Iowa or New Hampshire polls to qualify for the main debate.

The debate will be held at the North Charleston Coliseum and Performing Arts Center in North Charleston, South Carolina. The next debate—for Democrats—will be on 17 January and will be hosted by NBC News and YouTube.