Western Cape Premier Helen Zille is due to face a motion of no confidence in the provincial legislature on Thursday following her infamous tweets about colonialism.

Democratic Alliance (DA) Western Cape caucus chairperson Lorraine Botha and provincial chief whip Mark Wiley on Wednesday said they would not support the "baseless" motion.

"The content of the motion will be voted on for the third time now. The DA is not going to change... We will vote in confidence of the premier," Botha told journalists.

An urgent snap debate was also held immediately after Zille's initial tweets about colonialism in March, where she issued an apology, but also defended her stance.

The African National Congress (ANC) in the Western Cape has mooted an application for a secret ballot during Thursday's debate.

Wiley, though, said the ANC had missed the 12:00 deadline to apply for a secret ballot.

He suspected the ANC would make a big show of it during the debate in an attempt at "grandstanding", but that they should have followed the rules.

This will be the third motion of no confidence Zille has faced since re-election as Premier in 2014.

ANC Western Cape acting chairperson Khaya Magaxa told News24 that the DA had a case to answer to the nation.

"We are ready to debate. We are ready for the discussion, and for the DA to tell the nation whether they share their leader's sentiments praising 'positive' aspects of colonialism," he said on Wednesday.

'Internal ANC matter' to be dealt with

Magaxa, who sponsored the motion, would not be attending the sitting, as he will be dealing with "an internal ANC matter".

As leader of the opposition in the province, he had full confidence in the 14 ANC members who would take the issue to the governing DA.

He declined to comment on his party's internal provincial battles, saying the issue was now out of his jurisdiction, and had been taken over by the national leadership.

The debate will take place near the end of Thursday's sitting, around 17:00.

Zille faced a public lashing following her March tweets and subsequent apology three months later for her tweets about colonialism.

Zille and the DA agreed in June that she would step down from all positions in the DA, as censure, but would remain in her government position as premier until the end of her term in 2019.