SNP members have rejected a call for the party to implement a "plan B" for securing Scottish independence.
On the first day of the party's conference in Aberdeen on Sunday, a resolution by Inverclyde councillor Chris McEleny said that a pro-independence majority at the next election should be considered as a mandate for talks to begin with the UK Government over an independent Scotland.
In his speech to open the conference, the party's Westminster leader, Ian Blackford, had warned against members backing the proposal.
"When you hear talk of a so-called plan B, I ask you to consider this - the time to talk of a plan B is not when plan A has momentum," said Mr Blackford.
"And make no mistake - with rising support for independence and a general election on the horizon, we have that momentum.
"You know, plan Bs are by definition second best. That's why our opponents would love us to shift on to that ground - it concedes their right to block the best route to independence.
"And they will always settle for second best for Scotland. But we never should.
"When it comes to choosing Scotland's future, we should demand and win the gold standard for democracy and for our country."
Speaking in support of his resolution, Mr McEleny said: "I think that as a democratic political party, it's absolutely legitimate that we, the grassroots members of this party, have at least the opportunity to debate a plan B at our party conference.
"Plan A is the plan that we want to have. We have a triple-lock mandate for an independence referendum.
"What do we benefit from a quadruple-lock mandate, or even a fifth or a sixth mandate of continually winning elections when we have a usurper prime minister in Boris Johnson who refuses to accept the democratic mandate of Scotland.
"That's why I support a plan B and I think we should, at the very least, have a debate on it.
"You may not agree with the policy of having a plan B, but we are a democratic political party and vibrant political debate is what's made this party the party that it has been for 85 years and it's what got us to government in the first place."
He added: "Plan B is if Boris Johnson, an unelected Tory prime minister, if he refuses to give Scotland a Section 30 order so that we can have the referendum that we have the mandate for, then a pro-independence majority at the next election should be a mandate to enter straight into independence negotiations with the UK Government."
SNP national secretary Angus Macleod said that the conferences committee had already twice considered the resolution, but deemed that it had not been competently drafted.
"Clearly, if a properly drafted resolution was submitted to the conferences committee, we would consider that for a future conference," said Mr Macleod.
"However, this is not a question of debate, or the possibility of debate, we are always prepared for that in the conference committee and in this party, it is a proud tradition that we have.
"It is a question of whether we need competently drafted resolutions on which to have that debate and the committee was not convinced that we do."
Scotland in Union chief executive Pamela Nash said: "This was a direct challenge to Nicola Sturgeon on the conference stage.
"The SNP's splits on how to break up the UK show there is only one priority for the nationalists.
"It's telling that these debates aren't about how to improve our struggling NHS or our declining education performance, but about how to divide communities.
"The SNP will use every vote it receives in the forthcoming general election for its campaign for Scexit.
"The only way to grow our economy and protect vital public services for vulnerable Scots is to remain in the UK."
Speaking after the vote by members on the resolution, Mr McEleny said: "I fully accept the decision of conference delegates, who were swayed with the high-profile level of opposition, time will tell whether or not we do need a plan B.
"But the day an SNP representative decides not to progress an argument they believe in just because they're scared it might not be popular is the day we are worse off as a party, so I'm not down-beaten by the outcome and thank all the grassroots independence supporters for their kind words."