The broadside was launched by Harriet Harman, the Deputy Labour Party leader, who visits Scotland today to help her party win in a South Lanarkshire Council by-election, which, if successful, would lead to Labour taking control of the local authority.
Tomorrow, she will also be present at a Labour women candidates' meeting, which is to be attended by 80 Westminster hopefuls.
The Labour peer's attack comes after MPs agreed to transfer the power to hold the 2014 independence poll from Westminster to Holyrood with a so-called Section 30 Order but with a warning to Alex Salmond and his colleagues not to seek partisan advantage on key issues of the referendum question and campaign finance.
Lord McConnell will echo the point, accusing the Coalition Government of agreeing to "soft" conditions on the conduct of the independence referendum.
And he will say he is "angry" at the agreement.