The only thing that Helen Zille can do now is resign to save the Democratic Alliance (DA) a great deal of trouble.
Zille "just instantly become the weakest link", said political analyst Ralph Mathekga, director of research at the Mapungubwe Institute for Strategic Reflection.
"I'm just so shocked."
On Thursday, Zille was in transit from Singapore, waiting at OR Tambo International Airport in Gauteng when she sent out a series of tweets on colonialism that outraged South Africans.
I think Singapore lessons are: 1) Meritocracy; 2) multiculturalism; 3) work ethic; 4) open to globalism; 4) English. 5) Future orientation.
Other reasons for Singapore's success: Parents take responsibility for children, and build on valuable aspects of colonial heritage.
For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water etc.
Would we have had a transition into specialised health care and medication without colonial influence? Just be honest, please.
Getting onto an aeroplane now and won't get onto the wi-fi so that I can cut off those who think EVERY aspect of colonial legacy was bad.
I apologise unreservedly for a tweet that may have come across as a defence of colonialism. It was not.
Mathekga said it was particularly astonishing that someone in Zille's situation and with her political experience would put something like that out in public and she had damaged her own legacy. "What an injustice to the work that she has done in our society."
She has just written her own dishonourable exit from South African politics. She did it herself — Mathekga
She could have ended her political career with legitimacy but this changed everything.
"This is going to be one of those two or three defining moments of her political life," said Mathekga.
"Whether or not she retains her position as premier, the reality is that she has just written her own dishonourable exit from South African politics. She did it herself."
He said the DA would have to show consistency and discipline her, and referred to the case of DA MP Dianne Kohler Barnard, who was initially fired by the DA then reinstated but demoted, after sharing a Facebook post by journalist Paul Kirk calling for the return of apartheid-era president PW Botha.
"There has to be consistency. That is the problem," said Mathekga, saying that Kohler Barnard had reposted someone else's statement.
She authored it ... her tweets almost amount to a dissertation — Mathekga
"Helen Zille didn't retweet that statement, she authored it. And she authored a series, it was about three or four tweets in succession. For me, her conduct is more severe than that of Dianne Kohler Barnard. If I were in her position I would say: 'I've done a lot for the DA, I've tried my best, I have failed myself and the best thing I can do is to go'," he said.
"She has done it before. She has a pattern of doing this thing . . . She could get away with it. But this time, her tweets almost amount to a dissertation. It's not unclear, it's very clear.
"Here, she was very, very forward."
And now Zille has created a situation that other parties will rush to take advantage of, as the African National Congress (ANC) has already started doing.
"She has just created such a serious racial liability for the DA that the party's going to struggle to live with that. Some people think that this is just a once-off: no. It's a very serious thing. The ANC is going to have a field day, they've already started."
I think she was trying to provoke — Mathekga
Mathekga said that the political situation almost encouraged such behaviour.
"Government has serious legitimacy issues under the ANC and that has emboldened people, it has almost baited people to cross the line. I don't think that whites in general don't know when they are being racist, I think she was trying to provoke and she was trying to pass a political message."
And then later she realised the public relations nightmare she had created and attempted an apology.
But her apology isn't likely to help.
"The problem is that being seen as being next to Helen Zille now can easily be interpreted as endorsing colonialism. Who wants to be seen next to her?" said Mathekga.
"The best way will be for her to leave. These things should not be allowed in our society. There is freedom of speech but there is something that really really raises concern about someone who says that."