Shadow Scottish Secretary Ian Murray has warned Jeremy Corbyn that Labour is not seen as a credible future government - as one of the country's biggest unions gave the veteran leftwinger a year to prove himself.
Tim Roache, the general secretary of the pro-Trident GMB union, also suggested that Mr Corbyn faced a tough challenge ahead.
He was one of a series of critics who warned that the party should have won hundreds of seats in elections across the UK.
Instead, the party slipped to third in Scotland, lost its majority in the Welsh Assembly and saw dozens of English council seats change hands .
However, predictions that Labour could lost 150 councillors in England alone failed to materialise.
In response, Mr Corbyn claimed that overall the party was making progress.
He said: "All across England last night we were getting predictions that we were going to lose councils. We didn't.
"We hung on and we grew support in a lot of places."
But one veteran backbencher David Winnick called on the Labour leader to consider his position.
Mr Murray, Labour's sole MP in Scotland, also warned: "I don't think the public see the Labour Party…led by Jeremy Corbyn at the moment as a being a credible party of future government."
He called on the leadership to reach out more to a wide range of voters and to its own MPs.
He also suggested that more work was needed to make Labour's economic message credible.
Asked if Mr Corbyn had been a help, a hindrance or irrelevant to the Scottish result, Mr Murray replied: "A bit of all three".
Challenged that he was not giving a ringing endorsement of his party leader, he said: "I don't think the public are giving a ringing endorsement".
He rejected suggestions that he was putting Mr Corbyn on notice.
But other Labour MPs piled on the pressure.
Read more: Keep fighting for Labour values, Kezia Dugdale tells party members
Backbencher Jo Cox said that Mr Corbyn had to take responsibility for Labour's poor performance, adding that the results were "not good enough".
She said that she did not want or expect a challenge to the Labour leader's position, but she added: "The clock is ticking".
Another Labour MP Neil Coyle also said that he now regretted nominating Mr Corbyn for the leadership, saying Labour was "moving away from government" and attacking what he said was a "fixation" on "peripheral" issues like nuclear weapons.
Corbyn's allies like shadow cabinet colleague John McDonnell called on his critics to "put up or shut up".
Deputy leader Tom Watson also urged the party to be patient and respect the mandate Labour members gave Mr Corbyn last summer.
“'Patience', is what I would say to those colleagues who are coming out with intemperate remarks," he said.
But Mr Roache also hit out at MPs and urged critics to rally behind the leader.
He said : “We're at the stage when we should be winning hundreds of seats.
"But I don't think that's just about Corbyn, you know. People won't vote for a divided Labour Party.
"Therefore, those on the right of the party - or place them where you like - who are pushing against Corbyn, I don't think they're doing themselves a service, they're certainly not doing the party a service and most importantly from the GMB union's perspective, they're not doing working people a service at all and it's about time they rallied behind Corbyn.
"And let's give it a go. Let's give it a go for a year or so. Who knows what might happen.
"Leicester City won the Premier League only the other day. Who knows."
Communication Workers Union general secretary Dave Ward also called for “talk of coups and challenges to end”.
In Wales former Tory MP Neil Hamilton was elected to the Assembly as Ukip took 7 seats.
Labour also lost irs heartland of Rhondda to the Plaid leader Leanne Wood, who declared that a "new dawn" was breaking across the Welsh valleys.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereLast Updated:
Report this comment Cancel