The BBC's Martin Plaut profiles the two leading contenders to replace Tony Leon as leader of South Africa's opposition Democratic Alliance (DA) when he steps down.
Helen Zille, the feisty mayor of Cape Town, was a journalist with liberal Rand Daily Mail before entering politics.
Her greatest scoop came in 1977 when she uncovered how the black consciousness activist, Steve Biko, had been tortured to death, disproving the official version that he died of natural causes.
Elected to the Cape provincial parliament in 1999 she entered parliament in 2004.
Ms Zille became her party's spokeswoman on education. A fluent Xhosa speaker, she cultivated the DA's membership in the black townships around Cape Town.
In March 2006 she was elected mayor of Cape Town, and resigned from parliament.
Her position as mayor was fiercely contested by the governing African National Congress (ANC), which attempted to unseat her and the fragile coalition she leads.
But she has so far managed to see off the challenge and is one of the party's most high-profile campaigners.
Joe Seremane, the DA's chairman, is the party's best known black politician.
A former member of the Pan Africanist Congress, he has a long political record.
He was barred from teaching for his political activity.
Then he was imprisoned on Robben Island from 1963 to 1969, before being sent to internal exile.
There followed many years of detained without trial.
He became director of justice and reconciliation for the South African Council of Churches, before joining the Democratic Alliance in 1994.
He was elected chairman in 2000.
Once strongly black consciousness, he now rejects the politics of race.
His sister married a white man, leading him to reconsider his own position.
"I reflected on my own rhetoric and said: 'Joe, you want to cut the neck of every white person; and there is your sister who is going to have coloured children.'
"I started thinking why the struggle should be about power and not about race."
Seremane's brother was killed in the ANC's notorious "Quatro" camp in Angola, after he was accused of being an apartheid spy in 1982 - a charge he denied.