Donald Trump backlash intensifies within GOP ahead of first 2016 debate

Amid growing rancor among Republican presidential candidates ahead of their crowded first debate on Thursday, current frontrunner Donald Trump on Sunday threatened to consider running as an independent if he was not “treated fairly” by the party.

Related: All eyes on Trump as Republican debate nears, but Fox will be the real winner

In remarks that underscored the risks of attacking the maverick real-estate mogul too aggressively, Trump also warned that he would “counterpunch” just as hard if his opponents chose to make the debate in Cleveland personal.

Tensions have erupted in recent days, after Kentucky senator Rand Paul attributed Trump’s surprise lead in recent opinion polls to a “ temporary loss of sanity ” among Republican primary voters and former Texas governor Rick Perry claimed his impact on the race represented a “ cancer ” on conservatism.

Paul doubled down in an interview on Sunday, telling CNN there needed to be a more serious debate rather than “empty talk”. New Jersey governor Chris Christie also criticised “hyperbole” from other rightwingers such as Ted Cruz, who has accused the White House of sponsoring terrorism , and Mike Huckabee, who said the administration’s nuclear deal with Iran would lead Jewish people to the gas chamber .

Yet Christie, who has fallen behind in recent polling, also resorted to threatening metaphors when he added in the same CNN interview that the national teachers’ union deserved to be “punched in the face”.

The format of Thursday’s official debate, hosted by Fox News, may do little to tone down the fiery rhetoric, which has become a reliable way to stand out from the crowded field.

“The format only allows for one-minute responses and a 30-second rebuttal if we are attacked by name, so probably a lot of us will be sitting there hoping we get attacked by name so we can get a little more time,” said Huckabee in an interview on CBS.

Many of the 17 candidates are also angry at a decision to restrict the number of participants in the evening’s TV prime-time debate to 10 by choosing only those with the highest national poll ratings. The former Pennsylvania senator Rick Santorum, who came second in the primaries in 2012, said the cut-off was “arbitrary” and “irrelevant” on Sunday.

The latest national poll released by NBC and the Wall Street Journal suggests that some big names will fall outside the cut-off, including Santorum, Ohio governor John Kasich, Louisiana governor Bobby Jindal, South Carolina senator Lindsey Graham and former Hewlett-Packard chief executive Carly Fiorina, the only woman in the race.

All 17 candidates are going to be participating in debate night and I think that’s a wonderful opportunity

Reince Priebus

Republican party officials have defended the decision to limit participation, pointing out that the chasing pack will get a chance to debate separately before the main event.

“All 17 candidates are going to be participating in debate night, and I think that’s a wonderful opportunity,” Republican National Committee chair Reince Priebus told NBC.

Jim Gilmore disagreed. The former Virginia governor, the 17th and so far final Republican candidate to declare, and a former RNC chair himself, told CNN: “If I’m invited by Fox then I will probably go to Cleveland to participate to the extent that I’m permitted.

“But the fact is that this limitation by the RNC is improper. The RNC should never have put themselves in this kind of position. That’s not their job and not their role.”

Privately, many establishment Republicans are hoping the cull – however arbitrary – will help concentrate media attention on a smaller number of candidates in future and reduce the need to court publicity with inflammatory rhetoric that will later be used against the Republican nominee by Democrats in a general election.

But Trump, who has been accused by establishment favourite Jeb Bush of sparking the recent coarsening of the Republican debate, defended his approach on Sunday, arguing it was a fitting response to the challenges facing America, from immigration to Islamic extremism.

Related: Democrats add Donald Trump to list of serious Republican candidates

“They say the tone is too tough … [but] we need a tough tone. They are beheading our people. They are beheading Christians,” he told CNN. “The tone has to be tougher if we are going to stop Isis, if we are going to clean up the border and stop what’s happening, which is a disaster.”

He also spelled out his previously implied threat to run as a independent candidate, something that worries many who remember the impact of Texas businessman Ross Perot on George HW Bush’s re-election hopes in 1992.

“If I am treated fairly by the Republican party – and don’t win – I would have no interest in doing that,” Trump said when asked about running as a third party candidate.

“If I am not treated fairly by the Republican party, I very well might consider that and would simply not give that up.”

By: Dan Roberts in Washington and Martin Pengelly in New York

guardian.co.uk © Guardian News and Media 2015