He will have you know that his hair is real. In fact, while on the campaign trail in New Hampshire last month, real estate mogul Donald Trump let a woman up on stage touch his signature sandy coif.

But questions of whether Mr Trump is "for real" extends far beyond his head of hair.

From the get-go, many thought the reality TV star of The Apprentice was running for president of the United States for the publicity, and nobody expected him to get any traction.

But his brash statements have captured media attention while putting him on the path of becoming a party pariah.

He has called Mexican immigrants rapists and criminals, and most recently belittled Republican senator John McCain, a former prisoner of war, by saying he is "not a war hero".

Mr Trump, 69, quickly backtracked, adding: "He's a war hero because he was captured. I like people who weren't captured."

This latest comment at a forum last Saturday opened the doors for Republicans - already frustrated by Mr Trump's antics - to pounce, hoping to discredit his presidential bid.

Former Florida governor Jeb Bush, another presidential hopeful, tweeted: "Enough with the slanderous attacks. @SenJohnMcCain and all our veterans - particularly POWs have earned our respect and admiration."

Former secretary of state Hillary Clinton, aiming for the Democratic nomination, also weighed in, taking a stab at the Republican party at the same time.

"There is nothing funny about the hate he is spewing at immigrants and their families and now the insults he has directed at a genuine war hero, Sen John McCain," Mrs Clinton said. "It is shameful and so is the fact that it took so long for most of his fellow Republican candidates to start standing up to him."

Whether this blatant disrespect for war veterans will take down Mr Trump remains to be seen, but he has been doing surprisingly well in the polls. A Suffolk University/USA Today poll last week showed the billionaire leading the crowded Republican field with 17 per cent support among primary voters. Mr Bush is in second place with 14 per cent.

"Trump is making daily headlines in advance of the primary season," director of the Suffolk University Political Research Centre David Paleologos said. "This has vaulted him to the top of the pack on the backs of conservative voters."

Other experts say voter fatigue with more established candidates and, of course, Mr Trump's brand recognition after being on TV for years have given him a leg-up for now.

Although his brash comments about Mexican immigrants prompted companies to distance themselves from him - department store Macy's has dropped his line of products while NBC has cancelled The Apprentice - his strong stance on immigration evidently strikes a chord with some voters.

Slightly over a week ago, around 4,000 turned up for his rally in Arizona, where he stoked the anti-immigration sentiment once again and even allowed a father of a high school student killed by an undocumented immigrant to speak.

In a recent Gallup poll, 29 per cent of respondents said he would do a good job on immigration. Even more have faith in his ability to rebuild the US economy, with 36 per cent saying he would do a good job in that area if elected president.

That, of course, has much to do with his background as a successful businessman who, according to his campaign, has a net worth of more than US$10 billion (S$13.7 billion).

Mr Trump started his career working for his father, a property developer. The economics graduate from the University of Pennsylvania became president of the company in 1975 and renamed it The Trump Organisation. He also owns landmark buildings such as Trump Tower and Trump Palace in New York and golf courses all over the world. The father of five, who has been divorced twice, is also one of the highest paid public speakers in the world, reportedly receiving more than a US$1 million for an appearance.

He has filed four corporate bankruptcies - all related to casino property in Atlantic City - but never personal bankruptcy.

"I'm really rich... that's the kind of thinking you need for this country," he said when he launched his presidential campaign.

Mr Trump's devil-may-care attitude is perhaps a vestige of his childhood years. Reports say he faced "disciplinary problems" in school, which prompted his parents to enrol him at New York Military Academy for high school.

Some of his other plans if he were to become president include bombing oil fields in Iraq to counter the Islamic State in Iraq and Syria militants, rebuilding infrastructure, re-negotiating foreign trade deals and even building a wall to prevent illegal immigrants from entering the US from Mexico.

While people might be paying attention to him now because of the media circus he has created - he put reporters and gossip journalists in front of his podium when he made his official presidential announcement, instead of surrounding himself with supporters - many experts do not believe he is being taken seriously.

According to a Gallup poll, only one in four Americans considers Mr Trump a "serious candidate". This is the same as when he competed for the Reform Party's nomination in 1999, and he ultimately withdrew from the 2000 presidential race.

News website Huffington Post last Friday said it would stop political coverage of Mr Trump, and instead cover his campaign as part of the entertainment section.

Through all this, Mr Trump has remained unfazed. He told CNN earlier this month: "I'm in it to win it."