Tommy Sheridan was "set up" by the state and by members of the Scottish Socialist Party who were jealous of him, the politician's perjury trial was told.
Brett Harper, a social worker, told the High Court in Glasgow the former MSP was targeted because of his opposition to the poll tax.
Sheridan and his wife Gail, both 46, are accused of lying under oath during his successful defamation action against the News of the World newspaper in 2006.
The newspaper claimed he was an adulterer who visited swinger's clubs.
Mr Sheridan won £200,000 in damages after the newspaper printed the allegations about his private life.
Mr Harper, from Fraserburgh, Aberdeenshire, said he first met Sheridan as a student member of the SSP, when he organised events that the politician was to speak at.
He said he hosted similar events for Frances Curran and Colin Fox.
There was "a lot of jealously and bitterness" towards Sheridan within the party, he said.
He told Sheridan, who is representing himself: "I saw it myself.
"I organised for Frances Curran to come to Aberdeen. She was very keen to point out to people it wasn't Sheridan's Socialist Party, and that we had to get away from the almost-cult of Sheridan and make it a more open party.
"She made personal digs about you, about the whole sunbed thing.
"I'm sorry to say she also made digs about your wife for shopping in TK Maxx."
Under cross-examination from Advocate Depute Alex Prentice QC, Mr Harper added: "Tommy was set up by members of the state. I believe Mr Sheridan and others on the left have been targeted and the state was involved."
Sheridan is accused of making false statements as a witness in the defamation action of July 21, 2006.
Mrs Sheridan denies making false statements on July 31, 2006, after being sworn in as a witness in the civil jury trial.
They both deny the charges. The trial, before Lord Bracadale, continues.
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