John Swinney will call a vote seeking independence powers on the first day of the next Scottish parliament even if he fails to win an overall majority, his aides have said.

The Scottish National Party leader’s senior adviser indicated that if necessary, he would rely on support from the pro-independence Scottish Greens to win that vote in order to demand the UK government gives Holyrood the legal powers to hold a second referendum.

Swinney told his party’s conference last year that an overall SNP majority was the “clear and unambiguous” precondition for seeking those powers – a stance reinforced in the party’s 2026 manifesto.

However, a strategy document unveiled by Swinney on Monday, setting out what an SNP government would do in its first 100 days, did not specify whether a majority was needed.

The document said the SNP would “bring forward” a vote in early May on the parliament’s first sitting day if the SNP took power, without any preconditions.

Swinney was asked repeatedly by reporters to say whether that vote would take place if he failed to win a majority, and he refused to do so. The first minister stressed he would prefer a majority but added: “I’m simply saying to people, vote SNP and let’s get on with it.”

Swinney’s most senior policy aide told reporters the vote would take place even with a minority government. “You continue to pursue your agenda to the maximum amount, as all governments do,” he said. “If we’re elected as a government that manifesto stands. Otherwise what’s the purpose of a manifesto? The whole manifesto stands.”

The first 100 days document said the SNP would publish a draft referendum bill at a later date with the same yes or no question on independence from the 2014 referendum.

If it is produced, that draft bill would have no legal standing and would be highly unlikely to be formally tabled at Holyrood. Attempts to do so by former first minister Nicola Sturgeon were blocked by the lord advocate, Scotland’s chief law officer, because those powers are solely reserved to Westminster.

The supreme court ruled decisively in 2022 that only the UK government could legislate for an independence referendum – a decision that precipitated Sturgeon’s resignation as first minister. The UK government has repeatedly said it would refuse to approve a referendum.

Speaking on Monday, Swinney declined to say whether he would go to court in an attempt to force the UK government to delegate referendum powers if there was a majority vote at Holyrood.

He has previously claimed a legal challenge would be based on the precedent set by the decision of the then Conservative-led UK government in 2012 to give Holyrood the powers. The UK government did so largely because the SNP had won an overall majority in 2011.

Swinney’s approach appears to have been markedly softened. He said on Monday a majority was “an incredibly strong foundational argument” and did not confirm he planned legal action to secure those powers.

He made clear, however, that he wanted to prove to all Scotland’s pro-independence supporters that he was committed to making independence his utmost priority.

He said: “My message to people in Scotland who are independence supporters is that I’m offering a pathway for Scotland to have a choice to become independent [and] I would encourage any independence supporters to vote for the SNP to make sure that happens.”

Repeated opinion polls suggest that while the SNP is on course for a comfortable victory on 7 May, only about 75% of Scotland’s pro-independence voters will back the SNP. Many will support the Greens or other parties.

Russell Findlay, the Scottish Conservative leader, said “John Swinney’s plot to make the first vote of the new parliament about an independence referendum confirms how breathtakingly out of touch he is with the people of Scotland.

“Instead of focusing on the cost of living crisis, jobs, education or the NHS, he’s hellbent on plunging Holyrood into fresh constitutional chaos.”