The SNP would try to form an alliance to pursue “progressive policies” if the general election results in a hung Parliament, Nicola Sturgeon says.
But the SNP leader said the “reality” was going to be a Conservative majority government.
In an interview with the BBC’s Andrew Neil, she also said the cap on public sector pay rises was not “sustainable”.
Labour leader Jeremy Corbyn has ruled out a coalition between a Labour government and the SNP after 9 June.
Mr Corbyn has said he does not see the SNP as progressive.
In her BBC interview, Ms Sturgeon said the Labour leader was not “credible as an alternative prime minister”.
Asked whether her party would back Labour in key Budget votes if there was a hung Parliament, she said: “We will work for progressive policies and we will work for the policies we put forward in our manifesto.”
If there was a hung Parliament, she said “of course we would look to be part of a progressive alliance that pursued progressive policies” but predicted this would not be the outcome despite polls showing a narrowing of the Tories’ lead.
“Voting Labour in Scotland risks letting the Tories in,” she said.
Ms Sturgeon said she did not agree with Mr Corbyn’s plans to raise corporation tax – a key source of funding for Labour’s manifesto pledges.
And asked about her predecessor Alex Salmond’s claim that Labour was “copying” key SNP policies, she added: “Imitation is the sincerest form of flattery.”
The SNP launches its manifesto on Tuesday, and Ms Sturgeon promised to “get Scotland’s voice heard”.
She gave what she described as a “clear hint” on public sector pay, which is currently subject to a cap, saying future settlements should “recognise the cost of living pressures that public sector workers are having to live under”.
The Scottish government’s public sector workers are currently restricted to an average 1% pay rise in line with the rest of the UK, although it has offered extra help for the lowest paid.
Ms Sturgeon was also quizzed on her party’s record in government in Scotland, where it controls devolved policies such as health and education.
“I don’t sit here and say that we’re perfect,” she said of the performance of Scotland’s schools, but she insisted progress was being made.
The SNP leader, who is pushing for a second referendum on Scottish independence before the Brexit process has been completed, also set out her bid to keep Scotland in the EU.
She said it was her aim to maintain full EU membership, although if independence was secured after the UK had left, an interim arrangement might be needed to maintain single market membership.
Speaking on the BBC’s Sunday Politics Scotland, Scottish Labour leader Kezia Dugdale said people were “distressed, upset and worried” about the prospect of a second independence referendum and that it was her party’s job to block it.