Voters should forgive Allan Boesak's fraud and theft conviction as he served his prison sentence and received a presidential pardon, Cope's presidential candidate Mvume Dandala insisted on Thursday.

Dandala conceded that the cleric's candidacy for premier of the Western Cape had been questioned by many party supporters but said he was simply too good to sideline.

"We have been asked very directly by people, particularly since I arrived here in the Western Cape, whether we believe the Reverend Boesak is the kind of person we believe would represent our values," Dandala told the Cape Town Press Club.

"I've spoken clearly on Allan Boesak and his inspirational leadership. I have noted that were it not for the value of forgiveness I do not believe we would have the kind of South Africa we have," he added.

"We as Cope believe he has much to bring and add to our society."

Asked what distinguished Boesak from African National Congress leader Jacob Zuma, who faces charges of corruption and fraud linked to the arms deal, Dandala said there was a "major difference".

"Allan Boesak was tried by a court. He was found guilty. There is debate as to whether in the process there was any sense of repentance.

"(But) he went through his prison term, he was given parole and he was given a presidential pardon," said Dandala, who was fielded by Cope as a moral counterweight to Zuma.

"There should be a line at which you say you forgive."

Boesak rose to prominence in the 1980s as a churchman and a leader of the anti-apartheid United Democratic Front.

He served a brief jail sentence in 2000 after being convicted of fraud and theft of over R1.5 million of donor funds, but was later pardoned by former president Thabo Mbeki.

Boesak joined the Congress of the People in December but reports soon followed that he did so only after fruitless negotiations with the ANC in which he demanded a top posting abroad in return for his support in the April elections.

He insists that he was wrongly jailed for trying to help people in the anti-apartheid struggle and said the ANC was aware of the truth but did nothing to help him.