The Scottish Conservatives are "snapping at Labour's heels" for second place in May's election, leader Ruth Davidson has said.

As her party stakes everything on becoming the official opposition at Holyrood, Ms Davidson admits the strategy is "certainly ambitious" but insists it is achievable.

Just a few weeks into the election campaign, the Tory leader said her troops are feeling "positive, optimistic and resolute".

"We are in the hunt. We're snapping at Labour's heels, I don't think a couple of years ago anyone would have put us in that position," she said.

"The target that I've set my candidates, my activists, my staff, is that we want the best return we've ever had. We want the most number of votes, the most number of seats that we've ever had at a Holyrood election.

"That 's what I'm measuring them against and that's what I'm asking them to measure me against."

In an election where both the Liberal Democrats and Labour are proposing a 1p increase in income tax, the Tories hope their low-tax pitch will resonate with voters - despite criticism that pledges to reintroduce prescription charges and the graduate endowment constitute "hidden taxes".

Ms Davidson said: "We're the only party that is going into this election saying that we don't want to put your taxes up.

"We know that the SNP are putting up things like council tax by 3%, we know that they're putting up LBTT, the successor to stamp duty, we know that both Labour and the Liberal Democrats want to whack up income tax.

"I think that you don't grow your tax base, you don't grow the revenues that you have in your country, by sticking up a bloody great sign at Gretna that says 'higher taxes here, don't come and invest, don't decide to open an office here, don't build a business here, do it over the border'."

The Tory leader said her party was "ready to serve" as the official opposition, attacking Labour for "failing to land a glove" on the SNP.

She added: "I do feel that with four leaders in four years the Labour Party has been a bit chaotic in Scotland.

"I don't think that they've often put pressure on the SNP. I don't think that they've often held them to account in the way they need to."

Another key plank of the Scottish Conservative campaign is a staunch defence of the union.

Dismissing accusations it is her party that is stoking up constitutional division, Ms Davidson said: "I would happily never talk about it again if Nicola Sturgeon would just repeat the words that I challenge her to repeat any time, which said we're not going to have another referendum for a generation.

"If they are going to continue to agitate and threaten, then somebody has to stand up against them and if that falls to our party then so be it."

With around half of the Scottish Conservative parliamentary group retiring, the party is experiencing something of a changing of the guards.

New candidates were chosen in a selection process modelled on the potential officer assessments the army carries out for the Royal Military Academy Sandhurst.

Ms Davidson said: "We took the physical side of it out - there was no assault courses - but it was about the way in which the selection of officers for Sandhurst involves things like public speaking, ability to control conversations, time management, problem-solving, psychometric testing.

"We did want to make it quite hard to be a candidate because we think that if these are the standard-bearers for our parties then they should be people of real ability."

Ms Davidson, who supports "on balance" remaining in the EU, is dismissive of fears the ongoing referendum on membership and division between UK colleagues could undermine her Holyrood campaign.

While some polls suggest Ukip could pick up votes on the back of the EU vote, she said: "I remain to be convinced for a party that does not yet have a councillor in the whole of Scotland."