Theresa May will vow never to allow the UK to become "looser and weaker'' in a speech ahead of a meeting in Scotland with Nicola Sturgeon.
Manifesto 'Returns LibDems To Positive Agenda'
The Scottish Liberal Democrats' manifesto marks a return to the "positive, uplifting agenda'' seen under Charles Kennedy's leadership, Willie Rennie has said.
The proposals for Holyrood include key liberal commitments on policing, justice and civil liberties, alongside headline pledges on education and health.
The party won five seats at the last election, with opinion polls suggesting it faces a difficult task to increase that number on May 5.
But as he launched the manifesto at a soft play centre in Edinburgh, party leader Mr Rennie insisted the policies chime with public opinion in Scotland.
"People recognise that we are getting back to that positive, uplifting agenda that Liberal Democrats, perhaps under the leader of Charles Kennedy, adopted in the past,'' he said.
"Looking for opportunity, upbeat, asking people to pay a little bit more, making sure that we are outward looking, ambitious for the country.
"I think perhaps that has been missing in recent years, and I think we are back to it now.''
He added: "Our programme for Scotland is ambitious and progressive. We are offering the biggest investment in education since devolution, new plans for mental health services, new laws to guarantee our civil liberties and new investment so we can exceed our climate change targets.''
The Lib Dems' flagship policy, a "penny for education'' involves adding 1p to income tax for those earning more than #21,500 to raise around #500 million each year for education.
This would include giving schools thousands of pounds of additional funding through a "pupil premium'' aimed at raising standards and closing the attainment gap.
The party also plans to double free childcare to 1,140 hours a year for all three and four-year-olds, and will seek to do the same for all two-year-olds, with #100 million of additional funding.
It has further promised to restore college budgets and protect local authority education funding.
On health, the Lib Dems want to invest £500 million in mental health services over the next five years, and treble the #45 million primary care fund the Scottish Government is operating this year.
The document also includes plans for radical drug policy reform, with drug use to be treated as a health issue, a presumption against short prison sentences of less than 12 months, decriminalisation of prostitution, and the repeal of the Offensive Behaviour at Football and Threatening Communications Act.
The Lib Dems have promised to put power back into the hands of Scotland's chief constable and the Scottish Police Authority in determining police officer numbers, and keep the named person scheme ``under review''.
Mr Rennie said: "I think our agenda actually fits with the modern public mood in Scotland. I think people are much more relaxed about these issues - they see the value of a long-term plan to deal with the prison population, to deal with crime, to deal with drugs, to deal with prostitution.
"We are not reckless on these things. We want to try and help people and that's why having a longer term liberal approach to things, I think, chimes with people in Scotland now.''
Other pledges include a new Fit for the Future Investment Fund to tackle fuel poverty, and support for a system of land value tax to replace council tax.
On the constitution, the Lib Dems have said they would not support a second independence referendum in the next parliamentary term.
Vonnie Sandlan, president of the National Union of Students Scotland, said: ``This manifesto includes some really positive commitments for students and young people to ensure they have the necessary support to access education, stay there, and reach their full potential.
"The Scottish Liberal Democrats have set out clear policies to ensure improved support for our poorest higher education students, guaranteed and improved bursary support in further education students, and better support for young people with mental ill health.
"Those are the issues that students need to be at the heart of this election, and all parties need to deliver on.''
WWF Scotland director Lang Banks welcomed new policies on heating.
He said: "When signing the climate leaders' agreement last year, all of Scotland's political parties supported the idea of making energy efficiency a national infrastructure priority.
"While it's good to see the Lib Dems reiterate their support in their manifesto, it's a pity they did not build on this by setting out a level of ambition and budget.
"No matter the outcome of the election, we look forward to seeing politicians work together across the Parliament to develop a comprehensive action plan for delivering Scotland's climate change commitments.''
Scottish Labour environmental justice spokeswoman Sarah Boyack said her party would conduct an immediate review of the Scottish Government's land reform legislation, recently passed at Holyrood.
The use of Scottish Limited Partnerships (SLPs), which are exempt from tax as legal entities, have been questioned in light of the Panama Papers.
"We've also been calling for action to close the loopholes on Scottish Limited Partnerships,'' Ms Boyack said.
``It is extraordinary that Scotland is being described as a tax haven for shady companies to set up here.
``We'd also ban public contracts going to tax avoiders, and tax the richest 1% to invest in our schools whilst the SNP make Tory excuses to protect the richest.''
Campaigning in Edinburgh, party leader Kezia Dugdale also highlighted Labour's tax policy.
``Scottish Labour will guarantee that the education budget will not be cut on our watch. Labour will invest in the next generation by introducing a 50p tax rate and directing the proceeds straight into our schools,'' she said.
``We are able to make this promise because of the new powers that are coming to the Scottish Parliament and the fairer choices that we will make on tax. This is the least that Scotland's young people deserve.''
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