Donald Trump says he will forgo the overseas visits to allies in Europe, or even closer to home, usually made by leading Republican presidential hopefuls during their campaigns, insisting there is too much to keep him at home in the United States.

A visit abroad was still “possible”, Mr Trump said in response to a question from The Independent while on the campaign trail. But he added swiftly: “To be honest with you, this country is in such bad trouble, our infrastructure is crumbling, our bridges, our airports. We are in such trouble that I am going to spend a lot of time here … we are going to fix our country.”

Mr Trump, who has showed 28 per cent support among Republicans in a new poll by Quinnipiac University – 16 points ahead of nearest rival Ben Carson and with former Florida governor Jeb Bush on just 7 per cent – devotes large sections of stump speeches to foreign policy. He does so even as he admits that, for the time being, he retains no foreign-policy advisers.

A supporter of Donald Trump makes his feelings known at the Republican presidential candidate’s ‘Make America Great Again’ rally in Dubuque, Iowa, on Tuesday night (Reuters)

In the exchange with The Independent, he expanded on an earlier admission that he draws some of his foreign-policy thinking from television pundits, adding that he also scours print pages for their wisdom.

“I read many, many newspapers. I read a load of magazines,” he said. “I have people that I like and people I respect. You have a cross-section of really everybody because you see people that you really don’t have the opportunity to see or meet… From there you go and decide what you want to do.”

He will name one or more foreign-policy advisers in “two or three weeks”, he added.

At each campaign appearance – in Iowa on Tuesday and today in South Carolina – Mr Trump offers sometimes jumbled glimpses of what his foreign-policy vision will be. He brags that he will build up the US military – “I will have the best of everything” – but also distances himself from Republican hawks, excoriating the 2003 invasion of Iraq and arguing that the US should pick its fights and targets more carefully. “If you’re strong enough, you don’t have to attack anybody, because nobody’s going to mess with you,” he said this week.

As he shows he has staying power in the race, some of America’s brightest will surely be sitting up to take notice. Just as he promises to shake up the status quo at home, so he would on the world’s diplomatic stage.

Mr Trump has called into question Washington’s military commitments to Japan and South Korea, scolded Germany’s leaders for thinking the US would take on Vladimir Putin in Ukraine, chastised China for currency manipulation and criticised Japan for its trade imbalance with the US.

Donald Trump's most controversial quotes Show all 14 1 /14 Donald Trump's most controversial quotes Donald Trump's most controversial quotes On Isis: "Some of the candidates, they went in and didn’t know the air conditioner didn’t work and sweated like dogs, and they didn’t know the room was too big because they didn’t have anybody there. How are they going to beat ISIS?" Getty Donald Trump's most controversial quotes On immigration: "I will build a great wall — and nobody builds walls better than me, believe me —and I’ll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words." Reuters Donald Trump's most controversial quotes On Free Trade: "Free trade is terrible. Free trade can be wonderful if you have smart people. But we have stupid people." PAUL J. RICHARDS | AFP | Getty Images Donald Trump's most controversial quotes On Mexicans: "When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems. They’re bringing drugs. They’re bringing crime. They’re rapists." Getty Donald Trump's most controversial quotes On China: "I just sold an apartment for $15 million to somebody from China. Am I supposed to dislike them?... I love China. The biggest bank in the world is from China. You know where their United States headquarters is located? In this building, in Trump Tower." Getty Images Donald Trump's most controversial quotes On work: "If you're interested in 'balancing' work and pleasure, stop trying to balance them. Instead make your work more pleasurable." AP Donald Trump's most controversial quotes On success: "What separates the winners from the losers is how a person reacts to each new twist of fate." Donald Trump's most controversial quotes On life: "Everything in life is luck." AFP Donald Trump's most controversial quotes On ambition: "You have to think anyway, so why not think big?" Getty Images Donald Trump's most controversial quotes On his opponents: "Bush is totally in favour of Common Core. I don't see how he can possibly get the nomination. He's weak on immigration. He's in favour of Common Core. How the hell can you vote for this guy? You just can't do it." Reuters Donald Trump's most controversial quotes On Obamacare: "You have to be hit by a tractor, literally, a tractor, to use it, because the deductibles are so high. It's virtually useless. And remember the $5 billion web site?... I have so many web sites, I have them all over the place. I hire people, they do a web site. It costs me $3." Getty Images Donald Trump's most controversial quotes On Barack Obama: "Obama is going to be out playing golf. He might be on one of my courses. I would invite him. I have the best courses in the world. I have one right next to the White House." PA Donald Trump's most controversial quotes On himself: "Love him or hate him, Trump is a man who is certain about what he wants and sets out to get it, no holds barred. Women find his power almost as much of a turn-on as his money." Getty Images Donald Trump's most controversial quotes On America: "The American Dream is dead. But if I get elected president I will bring it back bigger and better and stronger than ever before and we will make America great again." GETTY

“You know, she’s a great leader,” he said of German Chancellor Angela Merkel in an interview with NBC earlier this month. “And one of the reasons that Merkel’s a great leader is she sort of says, ‘Oh, good. Let the United States handle it’.” At every stop, he claims the US has been taken to the cleaners in trade deals. He doesn’t say how he could undo or renegotiate them.

“We don’t have victories any more. We used to have victories but we don’t have them,” he said. “When was the last time anybody saw us beating, let’s say, China in a trade deal? They kill us. I beat China all the time, all the time. Who’s tougher on the Chinese than me? I love them and I have respect for them. I just hate what they do to [their currency].”

Mr Trump lambasts the nuclear deal negotiated with Iran but, unlike his rivals, stops short of vowing to rip it up. “Look at this deal. It is going to, in my opinion, lead to an arms race the likes of which there has never been. Countries are going to line up for nukes. You’re going to have, perhaps, nuclear proliferation. You’re going to see things that you have never seen take place in a short period of time.”