By Elisabeth O'Leary
GLASGOW, Scotland (Reuters) - The Scottish National Party (SNP) will start building a new case for independence from the United Kingdom this summer, party leader and Scottish government head Nicola Sturgeon said on Saturday, without committing herself to a timeframe for a new referendum.
Scots voted 55 to 45 percent against independence in 2014, but the collapse of the Labour and Conservative parties vaulted the SNP to unprecedented gains in the subsequent British national election in 2015, where it won almost all the seats assigned to Scotland in the parliament at Westminster.
"We want to be in the driving seat of our own destiny," Sturgeon told 3,000 delegates at the SNP's spring conference.
"This summer the SNP will embark on a new initiative to build support for independence," Sturgeon said, to a standing ovation.
"We will not achieve our dream of independence just by wishing that the outcome of the referendum had been different. Or wishing we could do it all again next week."
Senior British politicians, including Sturgeon, have said that if Britain votes to leave the European Union in the June referendum on that issue, but Scots show they want to stay, this could provide a trigger for a second Scottish secessionist drive.
The SNP will be campaigning for a vote to remain within the EU and polls shows Scots broadly support that view.
But there is division within the party about whether that is a coherent stance, as well as about how a British vote to leave the EU, or a Brexit, would affect Scotland.
Success would depend on the SNP's ability to present more compelling arguments for independence this time around, Sturgeon said -- a nod to the fact that some SNP insiders have criticised the last breakaway drive for being too dependent on the value of North Sea oil.
Many believe that much of the SNP's success is due to the popularity of Sturgeon herself, who took over the party leadership from Alex Salmond in 2014.
"Her positivity and confidence that we will get what we want eventually is just great," said Lorraine Alexander, a 57-year-old SNP campaigner, decked out in the party's yellow T-shirt.
Polls show that the SNP is favourite to win May's election for the Scottish parliament by a long chalk.
"I won't always get everything right," said Sturgeon. "Even if you don't always agree with me, I'll strive to be a First Minister you have confidence in."
One of the party's Westminster lawmakers said her popularity rests on a public understanding that she is genuine.
"Nicola's personal qualities are a big bonus and her very obvious personal belief is something that connects with people," said Peter Grant, an SNP lawmaker in Westminster, who was at the conference.
He estimated that it could take five to 10 years for another Scottish independence referendum to take place, depending on what level of support for independence is seen in polls.