NICOLA Sturgeon will this week use her first ­conference as SNP leader to move the party squarely on to Labour's turf ahead of the General Election, as she attempts to broaden the SNP's focus beyond the constitution towards issues of social justice and inequality.

In her keynote address in Perth next weekend, Sturgeon will say the SNP intend to occupy the territory of social and economic progress which has been "abandoned" by an increasingly right-wing Labour Party.

Although the SNP will always be the party of independence, she will say it also has to fight for a fair society and a strong economy. Writing in today's Sunday Herald, she says: "I want the SNP to be regarded as the party of social and economic progress for people. Labour abandoned the social justice agenda in Scotland, preferring to align itself with the transient trappings of Westminster power. By contrast, that agenda of a fair society bolstered by a strong economy is one that will be the daily business of the party and the Government I look forward to leading."

The rebalancing of SNP priorities is designed to capitalise on the malaise affecting the Labour party at both Holyrood and Westminster in the run-up to the general and Scottish elections.

Amid dismal personal poll ratings and private complaints from some Labour MPs that he is still failing to connect with voters after four years in charge, Ed Miliband was last week forced to deny claims his leadership was in freefall and insist that he would stay in the post.

Meanwhile, Scottish Labour is looking for a new leader after Johann Lamont's bitter resignation over the party being treated as a "branch office" by London and reeling from the loss of support in its former heartland areas in the referendum.

A new analysis issued yesterday by the SNP showed the party leading in the polls for the sixth week in a row, with YouGov putting it on 41% and Scottish Labour in 26% in terms of support at the General Election.

A senior SNP source said: "This is a big opportunity. The SNP can be the party of social and economic progress for people - which used to be Labour's ground - as well as progress for Scotland. They abandoned that when they walked off with the Tories in the referendum, and Nicola is signalling that we are here."

The new tone is designed to hold on to the thousands of Labour voters who were unhappy their party was working with the Tories in Better Together and who voted Yes in September.

It is an early sign that Sturgeon intends to stamp her own social democratic beliefs on the party as leader, and suggests a break with the more right-wing policies advocated by Alex Salmond, such as a 3p cut in corporation tax.

It is also recognition that the SNP must talk about something other than the constitution, or voters may see it as obsessed and out of touch.

Conservative MSP Murdo Fraser said: "Nicola Sturgeon is signalling that under her leadership the SNP will lurch to the left to fight Labour in its heartlands. This is very bad news for Scotland's business community and middle-class taxpayers will no doubt face the consequences of a more socialist agenda."

A Scottish Labour spokesman said: "In the same week the SNP again voted against a living wage, it also emerged that university education has become less accessible for students from the most deprived backgrounds. It's ridiculous for Nicola Sturgeon to say the SNP are a party of progress when for the last seven years they haven't introduced a single progressive policy.

"The next General Election is a clear choice between David Cameron, who wants to cut tax for the rich, or Labour who will tax the bankers to introduce a jobs guarantee for young people.

"Nicola Sturgeon knows that every vote for the SNP is a vote to help elect a Tory government. No Scot wants to jump into bed with the SNP and wake up with the Tories."

Sturgeon will be confirmed as SNP leader at the start of the conference on Friday morning.

Salmond will then give a farewell address in the afternoon, and Sturgeon will make her maiden speech as leader on Saturday.

However, she will not officially become First Minister until Wednesday, November 19, following a vote by MSPs and a swearing in ceremony at the Court of Session.