Ruth Davidson has pledged that her party would "break the old Labour-SNP stranglehold" on Scottish politics if elevated to the official opposition at Holyrood.

The Scottish Conservative leader said her party would bring a "genuine clash of ideas" to the Scottish Parliament if it achieves its ambition to overtake Labour for second place on May 5.

In a speech in Ayr, Ms Davidson accused Kezia Dugdale's party of failing to challenge the SNP on issues including educational attainment and plans to introduce a named person for every child in Scotland.

She said: "I have had enough of watching a party of government being whined at rather than challenged by the principal party of opposition. Who votes for their bills anyway?

"I've had enough of seeing political debate extend only to how much money can be spent, and how much can be taken out of the pockets of Scotland's workers.

"Consensus breeds bad laws and lazy thinking. It has given us named persons and an education system that is failing our deprived communities.

"Well, my message is that if we get more Scottish Conservatives at this election and if we become the main opposition party, we can break the old Labour-SNP stranglehold on Scotland.

"Scotland has not been well served by two left-wing parties battling it out to decide who can out-left the other."

Also out on the campaign trail, SNP leader Nicola Sturgeon launched a drive to highlight her party's record in government.

SNP candidates and activists will be armed with a document listing 131 "key successes" during what the SNP has dubbed "Active April".

The document cites record funding for Scotland's NHS, the extension of free childcare and school meals, free university tuition and the council tax freeze as top achievements.

The First Minister said: "The SNP is taking nothing for granted ahead of 5th May and this weekend - with hundreds more activists than we've ever had before - we'll take to the doorsteps to remind voters of our strong record in government.

"We've listed 131 top achievements of the SNP in government, but we're determined to make that 131 and counting - by winning a historic third term in government and continuing to build upon that record.

"Already in the campaign we've set a markedly different tone to our opponents, who are proposing tax hikes for families, while we're determined to protect household income, create jobs and grow our economy.

"Yes, we are proud of our record but we know that there is still much more to do.

"While Labour and the Tories scrap it out for second place, we'll maintain our focus on working towards a fairer, more successful Scotland for everybody who lives and works here."

The Liberal Democrats focused their campaigning on Scotland's police, saying they would increase resources and put an end to the "top-down targets culture that has seen morale amongst rank and file officers and staff plummet".

Speaking outside Police Scotland's Fife headquarters, leader Willie Rennie said his party would invest an additional £20 million a year to protect local services and jobs.

He said: "The SNP promised the creation of Police Scotland would save huge amounts of money and protect local policing. Instead, we have seen a budget black hole and suffocating top-down targets replacing local control.

"The latest budget papers from the police authority reveal that Police Scotland's costs exceeded its day-to-day budget by £22 million pounds this year. This is despite civilian staff and other support services being squeezed until the pips squeak.

"We will invest an additional £20 million to support day-to-day policing and protect jobs.

"This is over and above the Scottish Government's commitment to protect the police budget in real terms in 2016/17 which, on its own, will only embed the budget black hole and maintain unrealistic savings targets."