The Scot branded the Prime Minister "arrogant" after she insisted Nicola Sturgeon and the SNP had neglected the NHS and education in repeated bids to chase independence.
As May prepares for divorce talks with her European Union counterparts, Scottish leader Nicola Sturgeon has said Scotland was moving closer to its own breakup from the U.K. Sturgeon's Scottish National Party led an unsuccessful referendum to break away from the U.K.in 2014.
In a speech to party activists in Glasgow, the Conservative Party leader said that keeping England, Scotland, Wales and Northern Ireland together was her "personal priority" and there was "no economic case" for breaking up the UK.
"Our aim will be to achieve the most effective arrangements to maintain and strengthen the United Kingdom, while also respecting the devolution settlements, and we will work constructively with the devolved administrations on that basis".
But Mrs May made clear the UK must not become a "looser and weaker Union", adding: "We can not allow our United Kingdom to drift apart".
"I can't help but feel that the SNP has a tunnel vision about independence. I think the arguments are weaker and I think the people of Scotland are just as switched on as they were three years ago so I think there's every chance that we would win by a wider margin".
Sturgeon said on Friday that British ministers had "refused to seriously engage" with Scotland, offering a "brick wall of Tory intransigence".
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"The simple truth is their policies are not in the best interests of Scotland, but in the political interest of the SNP".
The Tory said: "My job right now is to stand up for the majority of Scots who say they do not want a second referendum, that is exactly what I'm doing".
"And yet the SNP propose Scottish independence, which would wrench Scotland out of its biggest market".
However Ms Sturgeon said they have constantly worked to reach a compromise over the terms of Brexit, only to be ignored an sidelined d by ministers in London.
The devolved Scottish government published a report in December that set out ways for Scotland to maintain its current position in the single market - which guarantees the free movement of goods, services and people within the bloc - even if the rest of the United Kingdom leaves. And according to a report in The Times, a senior Whitehall source dismissed vows made by the Vote Leave campaign to Scots during the European Union referendum as "another failed Michael Gove promise".
But the message was somewhat overshadowed by the awkward photographs that emerged after the Prime Minister was introduced in Glasgow by the Scottish Toy leader.