FORMER first minister Henry McLeish has claimed many of Scottish Labour's supporters no longer know "what the party stands for", and accused it of putting forward the "least attractive" Unionist plan on more powers for Holyrood.

The party had lost "enormous ground to the SNP unnecessarily" since 2007 by failing to connect with the public on basic voter concerns, the former Labour leader told the Sunday Herald.

His criticisms echo those of his fellow former Labour FM, Lord Jack McConnell, who yesterday said the party had lost its sense of purpose and vision since losing to the SNP and had become "a political machine" consumed by anger.

In a newspaper interview, McCon­nell said: "What we haven't had is an expression of what Scottish Labour stands for as we move through the 21st century. What is our purpose? Why should people support us? Why should we want to be the Scottish Government?"

He added that it was "staggering" the party no longer has a constituency MSP north of a line from Cowdenbeath to Dumbarton and said it was "running out of time" to rediscover its sense of purpose, its vision, and an ability to articulate the concerns of the people it represented.

The interventions add to the growing pressure on current Scottish Labour leader Johann Lamont to take the party in a new direction and win back the thousands of former supporters who turned their backs on Labour in the referendum and voted Yes.

Lamont has been dogged for months by rumours that she will not survive as leader until the 2016 Holyrood election, with Labour MP Jim Murphy and former prime minister Gordon Brown recently touted as alternatives who would stand a better chance against Nicola Sturgeon's resurgent SNP.

McLeish, who was first minister for 12 months in 2000 and 2001, said Scottish Labour had lost its way since the SNP came to power in 2007.

He said: "We've lost, over the last seven years, enormous ground to the SNP unnecessarily. We haven't gained traction on the real issues of Scotland. A lot of Labour voters don't know what the party stands for … [which is] essentially saying, 'Look, we're a party of social justice, we're a party of equality, not a party of unfettered markets.' But nobody knows about that now."

McConnell also denounced his party's devolution proposals as being the "poorest" to emerge from the Unionist camp.

Labour's submission to the Smith Commission on more powers was too timid and had been watered down by Labour MPs unhappy at the idea of losing influence at Westminster, he said.

All five parties with MSPs have submitted plans to a group headed by Lord Smith of Kelvin. Established to deliver the Unionist side's pre-election "vow" to voters, the commission is supposed to produce agreed plans by November 30 (St Andrew's Day), with draft legislation due by Burns Night (January 25), and full legislation after May's Westminster General Election.

Labour's proposals would see Holyrood raise 40% of its income, with more say over income tax, but not outright control of it.

The Conservatives and Liberal Democrats want income tax rates and bands fully devolved, with the LibDems also wanting many other taxes to be set by MSPs.

The Greens and SNP want virtually all powers bar foreign affairs and defence devolved.

An internal Labour commission set up by Lamont in 2012 originally proposed full devolution of income tax, but later adopted an unwieldy scheme giving MSPs the power to raise the top rate, yet made it harder to lower it again. The suspicion - denied by Lamont - was that Labour MPs are afraid of losing influence if Holyrood grows more powerful had forced a compromise.

McLeish said: "Labour had the poorest [internal] commission.

"If you take the three commissions [held by the Unionist parties], it had the weakest of the three. Partly, you know, because there's this tension between Westminster and Holyrood. Westminster, sadly, I think won.

"So they had the least attractive of the three commission proposals. But I know that a lot of people in the Labour party want to be bolder.Labour, I think, have to catch up with what [Gordon Brown] was advocating, and what some of the other parties are talking about."

Brown last week suggested giving Holyrood control over 54% of its income.

McLeish added: "I'm fed up with tribal politics, fed up with silo politics, fed up with manifesto policies. [The idea] one party can have a corpus of wisdom that is unique. That's the old stuff and we've got to move on."

The former first minister said he voted No in the referendum out of loyalty to the party and his family, but now feared Westminster would renege on its vow.

"I was the most reluctant No in this country. I think the Unionist parties are making a hash of it now. The problem is Westminster. The Union's in decline. They're failing, they're fading.

"When Cameron appeared on the doorstep, the votes were barely locked up in the box, and he said, 'Well thanks Scotland, it's over to England now'. It's so pathetic, so clumsy."

SNP MSP Sandra White said: "Henry McLeish is right, Labour are offering the least in terms of new powers, despite signing the vow which promised these would be 'extensive'. He correctly identifies that people have no idea what Labour stand for, apart from being the anti-SNP party, and they have gone further backwards under Johann Lamont even compared to the SNP majority victory in 2011."

Asked by the Sunday Herald about McConnell's remarks, Lamont said: "I have said since the beginning the Labour Party is a work in progress. The most important thing now is for people right across Scotland to come together. People want change. The Labour Party is going to be at the very centre of that."

A Scottish Labour spokesman said: "We will work constructively with the Smith Commission to give Scotland a devolution settlement that protects the benefits we get as part of the UK but give us more powers to help build a fairer society."