By Angus MacSwan
LONDON (Reuters) - Detractors have vilified her as the most dangerous woman in Britain and an existential threat to the United Kingdom.
New-found admirers have lauded her as an astute operator who has shaken up Britain's male-dominated political establishment.
Either way, Scottish National Party leader (SNP) Nicola Sturgeon has become one of the most talked about political leaders in the campaign for next Thursday's election.
Though a familiar figure in Scotland, Sturgeon was barely known south of the border until she put in a formidable performance in a televised debate between Britain's political party leaders on April 2.
"Sturgeonmania" said newspaper headlines after the debate.
Her emergence has gone hand in-hand with remarkable surge by the SNP, which lost a Scottish independence referendum in September that could have broken the United Kingdom apart, but has since quadrupled its membership.
It is now forecast to take most - perhaps even all - of the 59 Scottish seats in the 650-seat United Kingdom parliament, obliterating the Labour Party in one of its traditional strongholds and potentially making Sturgeon kingmaker if neither the Conservatives nor Labour gain a majority.
Sturgeon, 44, says the SNP occupies the leftist ground that Labour has abandoned. It promises an end to spending cuts and to protect the national health service. Although independence is still its ultimate goal, it has downplayed the issue for now and says that it wants to reflect the aspirations of all Britons.
"We won't just serve Scotland's interests - though we will most certainly do that," she told students at the London School of Economics. "But we will seek do more than that - we will also seek to play our part in bringing about positive, long-lasting and progressive change right across the UK."
All this has political leaders and right-wing media commentators fulminating from their perches in London.
The Daily Mail dubbed her "the Most Dangerous Woman in Britain". Its columnist sneered at her as "La Sturgeon" and mocked what he called her "choirboy mullet hairdo". The Sun tabloid photo-shopped a picture of her posing in a Tartan bikini, putting her head on the body of singer Miley Cyrus.
Conservative Prime Minister David Cameron said a Labour-SNP deal was a "terrifying prospect" and a "match made in hell". Former Prime Minister John Major said the SNP posed a "clear and present danger" to the future of the United Kingdom.
Yet Sturgeon has won many fans in England.
A poll in the Herald newspaper showed Sturgeon had the highest approval rating of any party leader across Scotland, England and Wales among men and women of all age groups, with a net approval rating of +33, compared to +7 for Cameron and -8 for Miliband.
"Nicola Sturgeon, a woman unknown to most English people until the leaders' debates, was deemed dangerous and destructive because, frankly, she seems so capable," wrote leftwing columnist Suzanne Moore in the Guardian newspaper.
In fact, it is not clear how much influence the SNP can wield in London after the election, even if, as polls predict, it controls the balance of power. Sturgeon has committed to keeping the Conservatives out, which leaves her little choice but to back Labour leader Ed Miliband as prime minister.
Miliband says he will not form a coalition with the SNP, effectively challenging Sturgeon to support him in a minority government or explain to her left-wing Scottish voters why she let Cameron keep his job.
Still, having a large and vocal party to his left could influence some of Miliband's policies, and force him to cooperate occasionally with the Conservatives to pass laws, such as renewing Britain's nuclear arsenal, which the SNP opposes.
"I AM LEADER"
Her popularity outside Scotland stands in stark contrast to her pugnacious predecessor as SNP leader, Alex Salmond, who resigned after last year's referendum defeat and is loathed in England.
An early Conservative campaign poster showed a picture of Salmond with Labour leader Ed Miliband in his jacket pocket. As Sturgeon broke onto the scene, the poster was changed to show Miliband in her pocket.
Although she played tribute to Salmond as a friend and mentor when he quit, there is still the potential for rivalry.
If he wins in his Aberdeen constituency, Salmond will take a seat in the House of Commons in London, while Sturgeon, who is not standing for a British seat, will stay in Scotland as party leader and first minister of the Scottish government.
Sturgeon has nevertheless made it clear that it will be her taking the train south for any negotiations in the event that the SNP secures the kingmaker role.
When asked if she had ever had a row with Salmond, she told the BBC: "Yes." When asked what about, she said: "I'm not telling you."
"The final say now as leader of the party is now mine.... That's how leadership works," she said. "I am the leader."
Sturgeon was born in the southern Scottish town of Irvine. Her father was electrician and her mother a dental nurse and she was educated at a state school. She graduated in law from Glasgow University and worked as a lawyer.
Her early political stirrings came through the Campaign for Nuclear Disarmament and she joined the SNP at the age of 16. She has spoken of "the scandal of soaring poverty in a country as rich as Scotland".
Elected to Scotland's devolved parliament in 1999, she became SNP deputy leader in 2004. When the SNP took power in Scotland in 2011, she became health secretary then later was in charge of infrastructure, investment and cities. When Salmond resigned, she was unopposed as the choice to succeed him.
She now speaks about a creating a progressive alliance at the seat of Britain's parliament, Westminster. But she has a warning for the British elite too: "It's an opportunity to give Westminster the fright of its life."