Grahame Smith, Scottish Trades Union Congress (STUC) general secretary, said the union was “disappointed” in the case being made for staying in the UK by the No campaign.
He made the stark claim as the umbrella trade union body launched an analysis paper on the referendum “a just Scotland” today.
The STUC, which represents, 630,000 workers, includes some of the UK’s biggest trade union such as Unite and Unison - that are affiliated to Labour.
Mr Smith said that STUC members had so far been “more attracted by the vision offered by the Yes campaign and the Scottish government” through their “social agenda on welfare and addressing inequality”.
“It’s fair to say that they’ve been largely disappointed by the lack of vision from the No campaign.”
Meanwhile, the STUC paper said that none of the currency options for an independent Scotland were “wholly compelling”.
It said that there were a “number of disadvantages” for the UK in agreeing to a currency union, but that a new Scottish currency under independence would “allow most discretion over fiscal and monetary policy”.