Alex Salmond has told his party's activists they can win the 2014 referendum if popular support for his devolved government can be converted into backing for independence.
The Scottish National party leader's appeal, as he opened the party's annual conference in Perth, came after a third poll this week showed falling support for leaving the United Kingdom.
Using Salmond's preferred referendum question of "do you agree that Scotland should be an independent country?," an Ipsos Mori poll for the Times found 30% in favour of independence, down nine points since January, compared with 58% support for staying in the UK, up eight points since January.
The spate of negative polls has soured the atmosphere for the SNP in the week that Salmond delivered a formal, legal agreement with his opponent, David Cameron, to stage an independence referendum in 2014.
The party is also facing a bruising dispute over whether the SNP should abandon its historic objection to membership of the Nato military alliance, with at least a dozen MSPs expected to vote against the motion on Friday. Party leaders expect to win the vote comfortably, arguing that joining Nato will not compromise their opposition to nuclear weapons, but persuade more voters to support independence.
In a tacit admission that most voters oppose independence, Salmond told activists that the SNP's critics had previously claimed the party would never see MPs elected, get a Scottish parliament or form the devolved government.
"Now they simply say we will never get independence; but we shall," Salmond said. "Delegates, make no mistake: we intend to win this referendum for Scotland."
Speaking after he had brandished the "Edinburgh agreement" he signed with the prime minister earlier this week to set up the referendum, Salmond said the pro-independence movement needed to persuade sceptical voters to trust his party to run a new country.
"We're now closer to our goal of Scottish independence not just in the 80 years of SNP history but in the last 300 years: that's what awaits the people of Scotland in two years' time."
Salmond said an SNP-commissioned poll by YouGov should give the party's opponents "pause for thought and us great cause for encouragement and that is the question of trust. Asked who do you trust to operate in the interests of Scotland, 64% said the Scottish government, 24% said the Westminster government: three to one, delegates."
The poll by YouGov did not in fact use the word "trust", but asked "in general, which government do you think is better at making decisions for Scotland?".
Salmond said that level of trust and confidence "gives us the platform to move into the referendum campaign. "If we're trusted because of our track record in administration, is that not the platform to say 'if you trust this government to run the health services, the education system, local government and social services, shouldn't we be trusted to run the economy, run defence, to run Scotland's international representation'?"
Salmond said the same YouGov survey for the SNP showed there was "a majority" in favour of Scottish independence when voters were told that every family could be £1,000 better off if Scotland left the UK.
In 2010, Scotland contributed 9.6% of the UK's tax revenue while only 9.3% of total taxation was spend in Scotland - a gap of £2.7bn.
The YouGov poll, which did not mention families being £1,000 better off but just "economically better off", showed the number of those "likely" to vote for independence would rise to 45%, against 38% who would still vote against it.
The conference, which lasts until Sunday, voted unaminously to formally join the Yes Scotland pro-independence campaign set up by Salmond earlier this year. Urging delegates to commit themselves to "the campaign of our lives", Nicola Sturgeon, the deputy leader, said it was now "game on".
The official pro-independence group now includes the Scottish Green party, Scottish Socialist party and Tommy Sheridan's Solidarity party amongst its members, and has reported that 100,000 people have signed up to its "yes declaration".