TO her excited followers she has become "The Sturgeonator," an unstoppable, super-human champion leading the SNP to previously undreamed of success.

To the Conservative-supporting Press, she is "the most dangerous woman in Britain," ready to drag a feeble Labour government far to the left, wreck the economy and dismantle the UK into the bargain.

Sitting down with such a formidable figure should be a daunting experience. But of course it isn't. "Nicola," as she is universally known, is that rare thing, a politician whose popularity transcends her own tribe. Where Mr Salmond inspired visceral loathing among opponents, Ms Sturgeon wins admirers. Since becoming Scotland's first woman First Minister last November, a ripple of approval has grown into a wave of public affection. The election has seen her riding higher than ever thanks to a series of polished television performances seen across the whole UK. Much of her appeal is down to the fact she is open and engaging, rather than the intimidating presence the headlines might have us believe.

Ms Sturgeon, 44, laughs off the suggestion she should have become a rock star to guarantee the kind of reception she has been receiving on the campaign trail.

"I can't sing, so it was never open to me," she jokes.

"It's not rock and roll, it's politics. It's the substance and the issues that matter.

"But having been in politics now for 25 years or so I've never known a time when people are as receptive to political discussion and debate.

"I like the fact that political debate seems to have come alive in Scotland

"There is a hugely different feel to this campaign from any other campaign I've been involved with, apart from the referendum which was a slightly different kind of campaign.

"Am I enjoying it?

"I'm enjoying feeling that you go out to campaign and you've got a population that wants to talk to you about it and is interested in it. I'm thoroughly enjoying it."

The latest poll of polls puts support for the SNP at a record high of 49 per cent, on course to win 54 of Scotland's 59 seats.

She admits she had expected the polls to narrow - so far there had been no sign of that - but says feedback on the doorsteps is "very positive" and she is "very optimistic" about the result on May 7. She stresses, though, her party must keep campaigning.

She makes no predictions about outcome across the UK, insisting the tight race between Labour and the Conservatives is a sign neither can fully convince the country of its merits.

She believes the Tories are panicking because Ed Miliband has failed to crumble as they hoped. David Cameron's repeated - and increasingly hyperbolic - warnings about a weak Labour government propped up by a dangerous cohort of SNP MPs - are a sign of desperation.

Ms Sturgeon does not accept her equally frequent forays south of the border and messages reaching out to voters in England, are helping the Conservative cause.

"From my point of view it's great. The SNP is the story, that means Scotland is the story," she says.

"It illustrates very clearly our central message.

"If you want Scotland's voice to be heard, vote SNP.

"They are all making that case for us right now."

At the SNP's spectacular manifesto launch at the Edinburgh International Climbing Arena on Monday, Ms Sturgeon was at pains to cast her party as a "constructive and responsible" ally for a minority Labour government.

If neither Labour nor the Conservatives command a Commons majority after May 7 her plan is this: her MPs would not support a Conservative government but would seek to make a minority Labour administration "bolder and better".

She says: "If we are in a minority Labour government situation, with a big team of SNP MPs, what we will be doing is trying to build alliances on an issue by issue basis.

"That will be trying to win support from Labour backbenchers as well as from Greens, if there are Greens and from Plaid Cymru MPs."

Her top priority is to force Labour to adopt the SNP's plan to increase public spending.

"I suspect there will be a lot of people on Labour's back benches who think that is the right thing to do," she adds.

Her call for Labour rebels to back the SNP's economic plans was undermined yesterday by the independent IFS think tank, which concluded that overall spending could be higher by 2020 under Labour's model.

It also illustrated the possible limits to SNP influence at Westminster even if the party takes the vast bulk of Scotland's seats.

But repeating her pledge to be constructive allies, she said: "I want us to go into this to effect positive change.

"It is not a case of us going to disrupt or bring down government at the first opportunity, or bring down a budget, we're trying to use whatever influence people here give us positively to get the kind of changes we are arguing for."

Another priority for SNP MPs will be to push for full fiscal autonomy, now rebranded as full financial responsibility.

Devo max, as it's also known, would blow a £10billion hole in Scotland's finances by 2020, according to the IFS, mainly because the country would rely on a trickle of oil revenues.

The SNP insist its can move to FFA (or FFR) gradually.

Mr Salmond has claimed the UK Government would be obliged to do that under a "no detriment" clause in the Smith Agreement on further devolution drawn up last year, a position dismissed by Chief Treasury Secretary Danny Alexander.

Ms Sturgeon said she will "negotiate" for the UK to fill any hole in the finances.

She said: "That is part of the negotiation.

"As powers are devolved that is one of the principles the Smith Commission set out.

"These things are all part of the negotiation.

"What we'd be doing is trying to get the best deal out of that."

The SNP's plans for full fiscal autonomy have come under sustained attack from opponents but Ms Sturgeon says Tory and Labour spending cuts are bigger issue for voters.

"That's where this election is being fought," she says. Her party's commanding lead in the polls suggests her instincts are right on that.