Shadow chancellor Ed Balls has urged Alex Salmond to meet him to discuss proposals to keep the pound in an independent Scotland.
The Labour MP is vying for the position of UK chancellor after the 2015 general election, which is likely to be held about nine months after the independence referendum in September.
Mr Balls pledged to honour the terms of the Edinburgh agreement, in which the coalition government pledged to work in the best interests of Scotland and the UK, and try to make independence work if Scotland votes Yes to independence and he is elected to serve in the government of the remainder of the UK.
He also expressed hope that Scotland would be able to join the European Union eventually, but said it would involve “some tough discussions with Brussels”.
But he warned that independence was “not going to be a good outcome for Scotland”, leading to higher taxes, higher interest rates, instability and uncertainty for investors.
Meanwhile, education and jobs took centre stage in the latest round of campaigning in the Cowdenbeath by-election.
Sports minister Shona Robison joined SNP candidate Natalie McGarry outside St John’s primary school in Rosyth to highlight the Scottish Government’s pledge to deliver free school meals for primaries one to three.
And Mr Balls joined Labour candidate Alex Rowley at Purvis Plant Hire, in Lochgelly, to make the case for voting Yes to Labour and No to independence to safeguard jobs and investment.
Mr Balls also insisted that “childcare is a more important need here in Scotland” than the provision of free school meals.
Scotland Office minister David Mundell joined Scottish Conservative leader Ruth Davidson and her candidate, Dave Dempsey, in Dalgety Bay, urging the SNP and Labour to quit the political “mud-slinging” and address local issues.
Scottish Liberal Democrat leader Willie Rennie insisted the SNP has “failed” in Fife on education and policing, and backed his candidate Jade Holden for Cowdenbeath.
The by-election, to replace the late Labour MSP Helen Eadie, will be held on Thursday.