He said he would only discuss golf, but in the end Donald Trump couldn’t help himself. The outspoken entrepreneur and Republican presidential hopeful used what was meant to be a brief trip to the golf course he owns in Scotland to declare that as US president he would “unite the world”, expand the US military and “get along very well” with the Russian president, Vladimir Putin.

However, in an extended and wide-roaming press conference, Trump went on to launch a bitter attack on his potential rival, Hillary Clinton – claiming the world “blew apart” when she was US secretary of state, while saying Barack Obama has been “incompetent”. He also weighed in on the possibility of a second Scottish independence referendum.

Evoking the memory of Ronald Reagan – to Trump, the last great American president – he accused the Obama administration of destroying the US at home and abroad. “Everyone hates us,” he said. Diplomacy, he added, was overrated.

“I think there’s been too much diplomacy. I think we’re so politically correct in our country that people are sick and tired of it and things aren’t getting done,” Trump said. “We’re diplomatic in our country and everybody hates us all over the world. We’re politically correct and the world hates the United States.”

Despite the bruising backlash over his tirade against Mexican migrants, which saw him accused of being racist, Trump insisted he was misunderstood. The US Hispanic community now lauded him as a visionary, he claimed.

“I think I would be a great uniter. I think that I would have great diplomatic skills; I would be able to get along with people very well,” Trump said. “I had great success [in my life]. I get along with people. People say, ‘Oh gee, it might be tough from that standpoint’, but actually I think the world would unite if I were the leader of the United States.”

As Trump spoke in the ballroom of his newly acquired hotel – rebranded the Trump Turnberry – on the rocky coastline of Ayrshire, south-west Scotland, tens of thousands of golf enthusiasts were below on its world famous championship course watching the main event: the Women’s British Open.

Trump now has three golf courses in Britain and Ireland; Turnberry is the crowning purchase. He bought it for £35m last year, and pledged on Thursday to spend £200m modernising it – double the previously cited figure. With it he also bought a course that would make him host of his first major European open tournament, the Women’s British Open, long booked to take place at Turnberry.

He had promised IMG, the event organisers, to restrain himself at the press conference, restricting questions to golf, Turnberry and the tournament. But Trump had other ideas, admitting that his business interests now took second place to his political ambitions.

“Now, pretty much my sole focus is running for president,” he said, pumping up his fame and frontrunner status in the Republican nomination race. “The latest poll is 25 [per cent] for Trump. Jeb [Bush] had 12.”

Trump at Turnberry on Thursday with his children Ivanka and Eric. Photograph: Jeff J Mitchell/Getty Images

Crowned with a red baseball cap with his campaign slogan, “make America great again”, tugged over his famous hair, and wearing the executive uniform of blue blazer, white golf shoes and crisp cream slacks, Trump had little intention of sticking to the intended script.

He made a half-hearted effort to focus questions on the event: Martin Ebert, the celebrated golf course architect, spoke briefly about the new greens and Turnberry’s heritage, while photographers shot frenetically as Trump stood at the back alongside his tanned and grinning daughter, Ivanka, and son, Eric.

Next Thursday, Trump will be facing Bush and the other Republican challengers for their first televised debate. He was not, he admitted, doing much preparation.

“As far as preparing for the debate, I am who I am. I’ve never debated before – I’m not a debater, I get things done. I don’t talk about it, I get it done. I’ll show up, I look forward to it, and that’s all I can do,” Trump said.

His pitch is simple: he says he will be America’s greatest selling point. “I think I would just get along very well with Vladimir Putin. I just think so. People say, ‘What do you mean?’ I just think we would ... Obama and him, he hates Obama. Obama hates him. We have unbelievably bad relationships. Hillary Clinton was secretary of state, she was the worst secretary of state in the history of our country. The world blew apart during her reign, now she wants to be president.”

He admitted that he had no idea what characteristics he shared with Putin, but the Russians loved him. “I think I would probably get along very well with Russia. I think I would probably get along very well with Putin. I think I would probably get along very well with the people of China.”

His global strategy is also simple: “I’d make our military much stronger and I’d make it so strong that nobody would mess with us.”

Asked which recent US president he most admired, he chose Reagan. Trump said: “He was somebody that the world looked to with respect; our country at that time was respected. If you remember the Iranian crisis with Jimmy Carter where they had our hostages, as soon as Reagan was elected, those hostages were released so quickly your head would spin. We were a respected country and he set a fabulous tone.”

Trump’s foreign policy mirrors trends on the right in recent years, notably conservative admiration for Putin, including from the former New York City mayor Rudy Giuliani, who openly praised him. “Putin decides what he wants to do and he does it in half a day,” Giuliani said in March 2014. “He makes a decision and he executes it. Then everybody reacts. That’s what you call a leader. President Obama – he’s gotta think about it. He’s gotta talk to more people.”

On Thursday, Trump also announced he would be adding a conservative kingmaker to his campaign staff: Michael Glassner, who was the director of vice-presidential operations for the John McCain-Sarah Palin ticket in 2008.

Challenged repeatedly by reporters over his remarks on Mexican migration, Trump insisted that Hispanic Republican voters agreed with him – as, he claimed, did many US voters upset by the “huge amount of turmoil and bedlam” caused by illegal immigration.

“The people are very thankful I was able to bring that argument out and crystallise that argument and I think you know that, I think you see that, and I think that’s probably [why I’m] number one in the polls, or one of the reasons,” he said.

He dodged several questions on his likely relationship with David Cameron, promising blithely that everyone would get on very well. But he bluntly dismissed talk of a second Scottish independence referendum as “ridiculous”.

“I thought that staying together was the better thing. I didn’t want to make my points very clearly on that, because I felt it wasn’t up to me. But I feel the people made the right decision and I can’t imagine they would want to go through that again.”

With that, Trump left the press conference, promised journalists the chance to tour his hotel’s fabulous new rooms with his son. Directly outside the hotel’s low white frontage, on a terraced lawn in clear view of the entire course, sat Trump’s red-lettered personal helicopter – an unambiguous statement of Trump’s burning desire for fame.