Republican debate as it happened: GOP candidates battle during first debate of 2016

And that's a wrap for the first primary debate of 2016.

The candidates are giving their closing statements:

• Kasich says he fixed the Pentagon budget and has stood up for seniors. I will continue to fight for you, he promises.
• Bush brings up his record in Florida and asks for voters's support.
• Christie continues his attack on President Obama and says he'll make sure Hillary Clinton does not win the presidency.
• Carson says that Americans need "We the People" instead of traditional politics.
• Rubio says Americans feel the US is changing and it's not a good change. Claims Obama wants to change the US and not fix it.
• Cruz gives a shout out to Michael Bay's upcoming film "13 Hours" based on the book on Benghazi by Mitch Zuckoff. He says if he's elected, he will have the back of the military and law enforcement.
• Trump discusses the Iranian incident "Iranian wise guys having guns to their heads," he said about the US Navy sailors detained by Iranian authorities. "If I'm president there won't be stupid deals anymore."

The debate is now going on 18+ minutes past the two hour mark. Prior to a commercial break, the moderators announced closing statements would be coming.

Rubio and Cruz battle on immigration reform and other issues Rubio accuses Cruz of flipping on.

Just before Kasich is allowed to speak, demonstrators appear to be shouting, "We want Rand!"

Trump is asked if he would probably have his children run his multi-million dollar companies if he were elected to the White House. "If I become president I couldn't care less about my company. I'd probably have my children run it," he said.

Rubio, meanwhile, takes a shot at Cruz over his proposed VAT-style tax. "That's why they have it in Europe, because it's a way to blindfold the people," Rubio said. "That's what Ronald Reagan said. ... That VAT tax is really bad for seniors.. they don't get the income tax break. But the prices go up. When I'm president of the United States, I'm going to side with Ronald Reagan on this, and not Nancy Pelosi, and we're not going to have a VAT tax."

Cruz argues that it is not a VAT tax but a 16% corporate tax.

In an ironic move, Christie is asked about infrastructure spending—fixing bridges and roads. Christie says he would levy a one-time tax on repatriating profits held by US companies abroad and use it to invest in infrastructure. "We'll tax it that one time at 8.75% — of $2tn, that's a lot of money."

The candidates have been discussing China and Trump's alleged proposal for a 45% tariff on Chinese goods. Rubio chimes in: "Best thing we can do to protect ourselves against China is to make our economy stronger."

Talk time update:

• Cruz 10:26
• Trump 7:49
• Bush 6:38
• Kasich 6:32
• Christie 5:17
• Rubio 4:14
• Carson 3:31

H/t @blakehounshell

Trump is asked again about his proposal to ban all Muslims from entering the US temporarily, which he stands by.

Former Republican contender Lindsey Graham, a darling of the undercard debates, is in the audience and is quoted in a question regarding military action in Syria. Carson, who barely knew what was being asked to him, is the first to answer.

There is no question that Isis is a very serious problem, I don't believe that this administration recognises how serious it is. I think we need to do a lot more than we're doing.

Cruz takes on the state of New York, and in particular New York City, by saying, "Not a lot of conservatives come out of Manhattan. I'm just saying." Trump, a New York native, takes offense and brings up the fortitude of New Yorkers following the 9/11 attacks.

I am confident if this president could confiscate every gun in America, he would.

- Marco Rubio

We're back from a brief break, Bush is asked "what is the harm in tightening" gun control such as background checks. Moderator Maria Bartiromo brings up Dylann Roof, who killed nine at a Charleston church. Bush says he disagrees with Obama's recent series of gun control executive orders but says Republicans and Democrats should work together on improving mental health help.

Following an exchange between Rubio and Christie regarding Rubio's criticism of Christie's supposed liberal policies, Bush jumps in and says that attacks during the campaign are expected but Republicans should unite behind the GOP nominee.

Rubio apologises for interrupting Cruz and Trump, saying he was sorry to interrupting the episode of Court TV going on the stage. He then says he'd use his presidency to repeal all the executive orders by Barack Obama.

A question everyone has been waiting for. Cruz is asked if he is a natural born citizen, thus eligible to run for president. The senator says that Trump, who has been promoting the birther movement, is only pushing those questions because his poll numbers are declining in Iowa.

Trump responds that his poll numbers are doing just fine. He's booed by the audience when he brings up the latest NBC/Wall Street Journal poll. He then admits he's now bringing up these questions because Cruz now has a better chance at being nominated.

Cruz asked about the New York Times piece that revealed he had failed to report two large bank loans to finance his 2012 Senate bid. After calling the article a "hit piece," Cruz says he simply made "a paperwork error."

After questioning all candidates, the moderators finally get to Donald Trump, who is asked bout migration to the US. "We cant let these people come into our country and break our borders," Trump said.

Florida Senator Marco Rubio continues the Hillary Clinton bashing, saying the former Secretary of State is disqualified from running for president.

If Hillary gets elected, she'll 'be back and forth between the White House and the Courthouse.'

- Jeb Bush

Jeb Bush says President Obama is wrong in saying that everything is going well in the world. Like the two candidates before him, Bush takes a hit at Democratic rival Hillary Clinton, calling her a national security disaster.

Where and when should a president use military action around the world. New Jersey Chris Christie said the US is not the world's policeman but he would use military action when and where American lives are at stake. Christie also calls out President Obama for his world view during the State of the Union.

Long-shot candidate John Kasich is up next, who is promoting tax cuts and "fiscal discipline". Despite not being an entirely too recognisable candidate, the Ohio governor has manage to qualify for all six main debates.

Question time: Ted Cruz is asked about jobs and he instead discussing the incident in Iran, where 10 US Navy sailors were detained after crossing into Iranian territorial waters. The Texas senator gets to the question but is buzzed as out of time.

Like the first event of the night, candidates have 90 seconds to answer questions and 1 minute for follow ups.

The national anthem has been sung and Fox Business Network is now playing its pre-debate teaser, including a countdown before the Iowa caucus and South Carolina primary.

With less than 10 minutes before the main debate, be sure to warm up with this gem from leading presidential contender Donald Trump's Pensacola, Florida rally on Wednesday (13 January).

With the main debate about to begin, let's take a look at where the seven participating candidates stand in the latest NBC News and Wall Street Journal poll. The party's top seven candidates stand as follows:

• Donald Trump: 33%
• Ted Cruz: 20%
• Marco Rubio: 13%
• Ben Carson: 12%
• Chris Christie: 5%
• Jeb Bush: 5%
• John Kasich: 3%

We are a few minutes away from the main debate, with the Republican Party's leading presidential contenders.

That wraps up the first part of the night! The main debate is set to begin in a little less than two hours.

The candidates are giving their closing statements. In his final comments, Santorum says he is going to take a few more moments to speak, since Rand Paul did not show up.

How would you strengthen the middle class?

• Fiorina blames the "political business class" for the decline of the middle class in the US. She also places blame on the tax code and big government.
• Huckabee says the government punishes the middle class with its tax code. "I really believe it's time to do something bold," he says.

Huckabee meanwhile is asked about entitlement programmes. In defending Social Security, he warns against raising the eligibility age and notes that with 4% growth, both Social Security and Medicare could be fully funded.

Santorum goes off about the risks of an electromagnetic attack triggered by a nuclear explosion in the upper atmosphere in the US and says Iran is attempting to do that to the US.

He then discusses illegal immigration and calls for 6M undocumented immigrants to be sent back to their countries. "We need to be the party that stands for the American worker. And that means if we need to send people back, we send people back."

The President keeps saying 'the gun show loophole'...there is no gun show loophole.

- Mike Huckabee

Next questions deal with President Barack Obama's latest executive orders aimed to curb gun violence. As expected, Fiorina and Huckabee are against the executive actions. Fiorina says the government should focus on enforcing the gun laws that already exist.

Santorum is asked if social media companies should be required by law to shut down terrorist accounts. He says no. Calls out bureaucratic nature of the US government.

The former CEO is also asked if the US should partner with Iran or Russia to fight against the Islamic State (Isis). Fiorina says, "Despite Donald Trump's bromance with Vladimir Putin...Russia is our adversary". She adds that the US should "stand and lead" in the fight against terrorism.

Fiorina says the US should stop allowing refugees into the country unless they're fully vetted. She also throws in the illegal immigration. Fiorina calls for a "pro-American" policy strategy.

When asked about situations in Iran, Afghanistan and elsewhere, Fiorina launches another attack on Clinton and the killings in Benghazi.

Huckabee and Santorum focus on the economy. While the former Arkansas governor tells the story of a working class woman who must work 15 hour days to survive, Santorum attacks President Barack Obama for focusing on climate change.

Fiorina answers first, makes a pointed dig at Democratic rival Hillary Clinton, and responds with an answer that sounds more like an introduction than a response to a question.

The night's first three candidates: Carly Fiorina, Mike Huckabee and Rick Santorum are on the stage. Candidates have 90 seconds to respond and 1 minute for follow up. The candidates delve right in with a question on the State of the Union.

The debate begins with a teaser from Fox Business Network that warns South Carolina can make or break a presidential campaign.

A fourth candidate, Kentucky Senator Rand Paul, was also set to participate in the undercard debate. However, after being bumped down from the main debate, Paul announced he would be boycotting the debate.

"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," he told The Washington Post.

The sixth GOP debate is set to begin airing at 6pm EST/11pm GMT with the undercard event, featuring the bottom three Republican candidates. The latest poll by NBC News and the Wall Street Journal reveal the bottom three candidates stand as follows among Republican voters:

• Carly Fiorina: 3%
• Mike Huckabee: 1%
• Rick Santorum: 0%