Former MSP Tommy Sheridan is to launch a new bid to overturn his perjury conviction.
The 50-year-old is set to take his case to the Scottish Criminal Cases Review Commission (SCCRC) in a fresh attempt to clear his name.
Sheridan said he is "supremely confident" his "unsafe" conviction will be quashed.
The firebrand socialist was jailed for three years in January 2011 after being convicted of lying under oath during his successful defamation action against the News of the World in 2006.
The now defunct tabloid printed allegations about his private life, which included claims that he visited a swingers' club and cheated on his wife. He was awarded £200,000 in damages after winning his defamation case against the newspaper at the Court of Session in Edinburgh.
But he ended up on trial for perjury at the High Court in Glasgow, where he was convicted of the charge at the end of 2010.
Sheridan - who was freed from prison after serving just over a year of his three-year sentence - has always maintained his innocence.
In 2011, he was refused leave to appeal against the perjury conviction. His legal team wanted to argue that he had been denied a fair trial because of the amount of publicity generated before it got under way, but senior judges found the case was "not arguable".
In cases where there has already been an unsuccessful appeal or leave was previously refused, the only route back to appeal judges is via the SCCRC.
Mr Sheridan will now urge the commission to look at his case, with his lawyers arguing he suffered a miscarriage of justice.
He is set to lodge a submission and supporting documents with the body in Glasgow, hoping it will refer the case back to the High Court for an appeal.
The SCCRC will firstly have to decide whether to accept the application. If it does, it then has to determine whether there may have been a miscarriage of justice, a process which usually takes a few months.
If the commission decides there may have been such a miscarriage, it would then refer it back to the High Court, and the case proceeds like a regular appeal.
Speaking in advance of the move, Mr Sheridan said: "I am supremely confident my 2010 conviction will be quashed. It was unsafe and unsavoury. We now have the proof required to expose the extent of the fit-up I was subjected to. The truth will out."
His lawyer, Gordon Dangerfield, said: "I believe that the submission and supporting documents which we are lodging with the Scottish Criminal Cases Review Commission present an absolutely compelling case that Tommy Sheridan's conviction for perjury was a miscarriage of justice.
"We seek that the commission refers the case back to the High Court for further appeal procedure.
"I believe not just that the perjury conviction will be quashed in due course but that Tommy will be completely vindicated."