Jeremy Corbyn will campaign for four days this week in Scotland in an attempt to revive the fortunes of Scottish Labor after a new slump in polling.

Labor sources admit that the party failed to take advantage of a wave of support during last year's general election when Labor defied the expectations by regaining six Westminster chairs from the Scottish National Party.

Corbyn's tour will give a speech in Glasgow on Monday, an event at the Edinburgh International Book Festival and visits to target sites in Lanarkshire, which Labor would have to regain from the SNP if it again won a quick election.

There is concern that not consolidating last year's earnings will threaten the broader strategy of the party. Of the 64 goal places in the United Kingdom, it has to win to regain power in Westminster, while 18 are Scottish constituencies owned by the SNP.

Prof. John Curtice, an election expert at the University of Strathclyde, said: "Scotland is absolutely crucial to Corbyn's hope of becoming prime minister."

After winning 27% of the Scottish vote at last year's Westminster election, recent opinion polls have put Labor third in the Tories with about 23%. After 11 years in power in Holyrood, the SNP's dominance of Scottish politics remains undisputed, while the nationalists question about 40%.

Those polls have raised concerns that Corbyn's appeal to former Labor voters who have defected to the SNP has disappeared and that too few voters have heard of the leader of Scottish labor, the left-handed Richard Leonard, or that they have not been impressed from him.

Sources from senior parties show that the Labor survey is much better than the 14% that it recorded in early 2017, but admits that they are anxious. Leonard is considered to be too reserved and is under heavy pressure to do more to increase his visibility, but he has resisted requests to enable the media to make personal profiles or to discuss his home life.

"We are plateaued, we understand that, but it is in a much stronger place than it was before", said a source of the most important parties. "We are fighting against two competing nationalisms and Scotland is still being influenced by the constitutional debate in 2014. To come from where we were before is progress, but much more progress needs to be made and we understand that."

Curtice said: "Labor is alive in Scotland [but] it still has a long way to go, returning to something like the level of support it had 10 years ago. "

Leonard said he was optimistic. "We may be on an electoral foot for a general election possibly later this year, and I think this can not come soon enough, on 10 seats we need about 1% swing to get those chairs from the SNP," said he.

"I am reasonably philosophical about the fact that we have three years until the next Scottish parliamentary elections, so by the time we arrive in 2021, I hope that my position will be increased in the eyes of the Scots."

Corbyn's central critics argue that the British leader of the party in Scotland is much less powerful than his supporters think, and the dip of Labor links to his position on leaving the EU. They accuse the Scottish party of failing to tap into greater hostility towards Brexit than in most other parts of the UK, and argue that the SNP leader, Nicola Sturgeon, reflects that antipathy much more successfully than Labor, especially among the middle class voters.

They also believe that the recent controversy over Corbyn's attitude towards Israel has damaged Scottish support in key constituencies.

They say the first major antisemitism row in May 2016, comments on Hitler and Zionism by Ken Livingstone, a supporter of Corbyn, the voice of Labor in the Scottish elections and contributed to the loser of East Renfrewshire, home to the largest Jewish community of Scotland.

A leading Corbyn critic said the current row showed "his past is coming back to haunt him".

Matt Kerr, a Labor Councilor who came in 60 votes last year to win Glasgow South West from the SNP, said about the current polls: "We have to be honest that there is still a long way to go."

However, he said that Corbyn "had given us a support with voters".

"The socialist message was lost in the constitutional battles and we have had to work hard to be heard again." As a third party we do not get the airplay we were accustomed to, but at least we do not behave like a rabbit in the headlights, " he said.

"We know what we are for and that is due to a solid policy platform and the influx of younger, highly motivated members."