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 secure 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."