The Prime Minister has warned that Scotland is in "danger" of becoming a "one-party state" under the SNP.

In his speech to the Scottish Conservative conference in Edinburgh on Friday David Cameron claimed that Scottish Labour’s collapse means his party must become the official opposition.

He told delegates: "We’re the party that can challenge the SNP – now the only party that can challenge the SNP.

"They’ve been in power for nine years – they are the establishment. And with Labour’s collapse, Scotland is in danger of becoming a one-party state."

The SNP holds a majority of seats in the Scottish Parliament, 54 out of 59 Scottish seats in the Commons, and a plurality of councillors north of the border. Polls suggest the party will increase its majority at Holyrood after the May elections.

David Cameron also stated that the Scottish Conservatives are aiming to replace Labour as Scotland’s second largest party, "For the next 62 days we are going to fight to become the official opposition."

It has almost been a quarter of a century since the Scottish Conservatives came second in a national election in Scotland. In last year’s UK general election the Scottish Conservatives finished up with only one seat and 14.9% of the vote.

However many Scottish Conservative figures are talking up their party’s chances in the forthcoming Scottish Parliament elections.

The Conservative leader was heavily critical of the SNP's record in government.

"Look at their litany of failure. Children’s school attainment – stagnating. The number of college students – falling. Help for poorer students at university – cut. Increasing health spending like England – unfulfilled. Then there’s the mess of the law that bans football songs. There’s the lost accountability of merging eight police forces into one.

"There’s the abolition of Right to Buy – yes, even though Nicola Sturgeon’s family benefited from it, she’s saying that you can’t. There’s even the absurd Named-Person policy, which ensures every child is allocated a guardian – even if they have parents; even if they have no need for this extra layer of bureaucracy.

"Well I'll tell you who needs a guardian – someone to keep them in check – it’s the SNP."

STV’s latest Holyrood election poll with Ipsos-Mori showed that the Scottish Conservatives are heading for third place on 16%, behind Scottish Labour on 20%. Both parties found themselves significantly behind the SNP on 53%.

Report by Aidan Kerr, STV’s digital politics reporter. You can contact him at aidan.kerr@stv.tv.