Such a move, the theory went, would prove popular with voters who, according to survey after survey, seem to like the idea of a beefed-up Holyrood more than either the status quo or independence.
It would also help silence accusations from the Nationalists that any vague, conflicting promises of more powers would quickly melt away after a No vote.
Ken Macintosh's intervention in Scottish Labour's internal devo debate shows just how difficult it will be for the pro-UK parties to pledge more powers for Holyrood and convince voters they really mean it.
Labour's divisions over devolution threatened to overshadow the party's conference in Inverness last year and could do so again when members gather in Perth next month.
Remember, Mr Macintosh's staunch opposition to fully devolving income tax is only one half of the story Johann Lamont's devolution commission has to listen to. Public sector union Unison, for example, wants the party to embrace much deeper devolutuion - not just full income tax but elements of pension and energy policy too.
The Tories, meanwhile, are still in the early stages of drawing up their devo plans leaving only the LibDems with a fully fleshed policy, in their case for a federal UK with wide tax powers transferring to Edinburgh.
It may be the Better Together parties can do no more than promise to work together and hope that is enough to persuade voters of their rock-solid commitment to ...something.