Liberal Democrat leader Tim Farron has hit out at the "ugliness" of some parts of Scottish nationalism as he called on Nicola Sturgeon and the SNP to "take the chip off your shoulder".
Mr Farron claimed the the SNP administration in Edinburgh had "failed the Scottish people" as he attacked their "sticking-plaster solutions" to problems in the NHS and education.
With the Scottish First Minister also warning that June's European referendum could trigger a second vote on independence if Scotland votes to stay part of the EU but the UK opts to leave, he also demanded the SNP "start pulling the finger out" in the campaign to remain.
The Liberal Democrat leader condemned the "grievance" politics of the SNP.
He told the party's Scottish spring conference in Edinburgh: "There is sadly an ugliness to some elements of Scottish nationalism which many of us in the rest of the United Kingdom simply don't see.
"We saw it during the referendum, with SNP candidates and campaigners alike seemingly determined that no other views than their own should receive a hearing."
But he added: " Our message to Nicola Sturgeon and the SNP is clear - it's time to take the chip off your shoulder.
"Let's put grievance and division behind us and focus on the things that really matter for Scotland."
The Liberal Democrat leader later told journalists he would share a platform with Ms Sturgeon, David Cameron and Jeremy Corbyn in the campaign to keep Britain in the EU - warning a vote to leave could result in " the loss of access to a market worth £80 billion a year, the ability to work with others to tackle climate change" and would also damage the UK's international standing.
Mr Farron said: " My sense is the nationalists should stop talking about what would happen if we lost the referendum and start pulling the finger out and do something to help us to win it."
He told the conference that the vote on whether or not the UK should remain part of the EU is the biggest decision for a generation, insisting that staying in "is a no-brainer".
Mr Farron insisted: "The only party that is wholly in favour of a Scotland that is prosperous and s ecure within Europe and the United Kingdom is the Liberal Democrats."
With Scottish Parliament elections taking place in May, he said he is hopeful the Lib Dems, who currently have just five MSPs, would grow.
Mr Farron said he sensed "clear movement" against the nationalists, saying: " Two things don't help the SNP. One is a realisation that this is not a referendum, this is about whether or not the country is well-run, and there is a sense that the SNP is not a good administration, and I'm being very kind to them there.
"The second thing is the Scottish sense of fairness and how uneasy people feel about the dominance of one party across Scottish politics."
Speaking about the Lib Dems, he said: " Against the odds we're in really good form. We start from a difficult set of elections last May, but our fightback has been remarkable."
His speech to the conference included a strong attack on the SNP, who have been in power in Scotland since 2007, on issues such as health and education.
Mr Farron said: "Nicola Sturgeon and her colleagues chose to let the health budget slip. The effects have been devastating.
"Dozens of children have been forced to wait more than a year to receive specialist mental health care.
"A&E waiting time targets have been missed and missed again.
"Meanwhile, more and more has been wasted on sticking-plaster solutions and so-called action plans that have not given our doctors and nurses the support they need."
He also said that SNP promises on early years care had been "broken" while college places have "vanished".
The Liberal Democrat leader said: "You can't just wrap yourself in the flag and hope no-one notices that you have failed the Scottish people."
Mr Farron said the Liberal Democrats must "challenge the SNP's arrogant sense of entitlement to rule".
He told the conference: "They act like you have no right to vote any other way. We will not have that. We need to remind the SNP that theirs is not the only voice in Scottish politics, that they do not have all the answers."
He also insisted: "W e must celebrate the positive future that is a European Union prepared to work together to tackle the great challenges facing the world - from climate change and changing global markets, to the mass migration of people who are displaced by war and instability."
Mr Farron launched a fierce attack on Mr Cameron over the refugee crisis that has swept Europe, saying while the UK Government had committed £2.3 billion "that is all money destined far from our shores, and, more crucially, far from the shores of Calais or Dunkirk, Lesbos or Lampedusa".
He claimed the Prime Minister wanted to "keep the refugee problem away from us, out of sight and out of mind".
But Mr Farron said: "B ritain is a fair, compassionate and tolerant country. Scotland is a fair, compassionate and tolerant country.
"By failing to act to support the weakest, most vulnerable people on the planet, David Cameron is letting us all down."
He demanded the Conservative Prime Minister show " some leadership, show some backbone", as he pledged he would keep pressing the issue.
He said: " As Mr Cameron shamelessly banks on the British people losing interest, getting compassion fatigue, outrage fatigue, I will pursue Mr Cameron until he gets Farron fatigue, and gives in and does the right thing, the British thing, to take our fair share of refugees to provide sanctuary for those children alone in the camps."
The Liberal Democrat leader went on to attack the Conservative Government on the environment, saying between 2010 and 2015 his party had " fought sceptical Tories to ensure the coalition was the greenest government ever".
However he claimed: "I n the last six months this progress has been unravelled at an alarming pace. It is shameful that the work we began in coalition to deliver is being unpicked."
Mr Farron went on to attack Labour, saying Jeremy Corbyn's party " make me genuinely angry".
He told the conference this was "n ot because they've been taken over by the kind of people who used to try to sell me tedious newspapers outside the students' union, not because they've got a socialist leader... But because they are the most useless opposition in the history of British politics".
SNP MSP Kevin Stewart said: "Tim Farron has a cheek lecturing the Scottish people after the Lib Dems kept the Tories in power for five years - during which they forced austerity and hated policies like the bedroom tax on Scotland.
"The SNP will be making a positive, progressive argument for Scotland's place in Europe over the coming months - Tim Farron should ditch project fear and make the positive case for EU membership."