The Prime Minister made an ambitious bid to capitalise on growing Tory support north of the border, where the party has only one MP, saying she would ensure Scotland and the UK “flourish together”.
In the rural village of Crathes, Aberdeenshire, where TV channels were unable to broadcast live and several journalists complained of a lack of mobile signal, Mrs May reiterated her call for voters to back her to strengthen her hand in Brexit negotiations.
It came after Mr Corbyn accused her of slipping into a “presidential bunker mentality”, reliant on sound bites and squeezing dissent, and claimed her attitude could lead to “damaging mistakes” for the country.
Scotland’s First Minister Nicola Sturgeon reacted to Mrs May’s foray north by urging voters not to allow the nation to be “dragged back” by an “increasingly hard-line right wing Tory Government” in Westminster.
But Mrs May’s visit to northern Scotland underlined the size of the election victory she thinks is within her grasp, with the Tories now the leading unionist party north of the border, according to opinion polls.
Making a direct plea to Scottish voters who oppose independence, the PM said: “We want to ensure that we build a more secure and united nation.
“That means taking action against the extremists who would divide us and standing up against the separatists who want to break up our country.”
Mrs May went on: “There is only one candidate for prime minister who will stand up and defend the United Kingdom. And my commitment is clear that if you strengthen my hand in those Brexit negotiations, I will work to ensure that Scotland and the UK flourish together.
“So on June 8 vote for five years of strong and stable leadership. Give me the mandate to lead Britain, give me the mandate to speak for Britain, give me the mandate to fight for Britain and give me the mandate to deliver for Britain.”
Mrs May spoke after Mr Corbyn addressed supporters in the Labour stronghold of Whitechapel, east London, in his most personal speech of the campaign so far.
He compared Mrs May to Tony Blair, whose premiership he said showed what can go wrong if leaders go unchallenged because his Labour government “bought into Conservative ideas” about the economy that left Britain with no defence against the global financial crisis.
The Labour leader said Mrs May is “insecure” because she wants more power, while he would empower others if he is elected PM.
“If leaders go unchallenged, they can make some of the most damaging mistakes,” Mr Corbyn said.
“And if party leaders put themselves ahead of serving the people, they stop listening and even put our country at risk.
“Barely nine months into Theresa May’s premiership, there are clear warning signs that she and her closest advisers are slipping into that presidential bunker mentality.
“Whereas it is the job of leadership to hold open the space for dissent, new thinking and fit-for-purpose policy.
“So while it might not be the stuff of sound bites, I have always believed in standing firm and empowering others to make up their minds and come on board when they are ready.”
He added: “It is the mindset that serves the many, not the few.”