SNP Westminster leader Stephen Flynn has called for the Prime Minister to resign over his "shameful role" in the appointment of Peter Mandelson.
It comes as Sir Keir Starmer is set to face the scrutiny of MPs in a statement to Parliament on Monday over reports that the former US ambassador was appointed despite failing vetting for the role.
Mr Flynn has urged Scots to vote SNP to "show Keir Starmer the door" after all "the lies and broken promises".
"On 7th May, people in Scotland can vote SNP to sack Keir Starmer and secure a fresh start with independence.
"It's clear Keir Starmer has no intention of doing the honourable thing and resigning over his shameful role in the Peter Mandelson scandal - but voters in Scotland can show him the door by voting SNP on 7th May.
"The political reality is - Keir Starmer will use every vote for the Labour Party as an endorsement to cling onto power and deny people in Scotland a choice over our future in an independence referendum."
Prime Minister Sir Keir Starmer is set to face scrutiny from MPs on Monday (Tom Nicholson/PA)
Lord Mandelson was sacked last year, less than a year into the job, after details of his association with the paedophile financier Jeffrey Epstein emerged in files published by the US government.
The Foreign Office has been blamed for clearing the peer in January 2025 to begin as US ambassador, despite him failing a secure vetting process.
The Prime Minister has said he was "absolutely furious" and described the failure to inform him as "staggering".
Sir Olly Robbins, who was only weeks into his job as Foreign Office permanent secretary at the time, was sacked on Thursday as he had lost the confidence of Sir Keir and Foreign Secretary Yvette Cooper.
Mr Flynn continued: "Labour MPs publicly, and privately, admit a majority for the SNP in Scotland will be a key deciding factor in removing Keir Starmer from office and delivering a fresh start with independence.
"Voting SNP is the only sure fire way to show Keir Starmer the door after all the lies and broken promises - and every vote will count.
"The constant chaos and soaring cost of living under Westminster control shows why Scotland needs the fresh start of independence and full control over our huge energy wealth to lower bills, protect our NHS and build a fairer, prosperous future.
"That is what the SNP is offering on 7th May."
Scottish Labour deputy leader Jackie Baillie said: "Once again the SNP is trying to deflect attention elsewhere because it cannot defend its own shameful record in government in Scotland.
"This election is about Scotland's government, our NHS, our schools, our local services, our community safety and our transport system - all of which have been run into the ground by an incompetent and out of touch SNP government.
"This election is a direct choice between a third decade of John Swinney and the SNP and a fresh start with Anas Sarwar and Scottish Labour."