ANC MPs were summoned to a special caucus meeting yesterday, attended by Deputy President Kgalema Motlanthe, at which the motion of no confidence was discussed.

The opposition parties proposed the motion in terms of section 102 of the constitution, which stipulates that, for such a motion to succeed, the support of more than half of all members of the National Assembly is required.

The ANC holds 264 of the assembly's 400 seats and the opposition parties would have needed at least 67 ruling party legislators to support the motion for it to pass.

But ANC MPs have chosen to rally around Zuma by refusing to allow it to be debated in the National Assembly.

"The motion of the opposition about the alleged violation of the constitution by President Zuma is without foundation and cannot be supported by fact," said ANC chief whip Mathole Motshekga.

This is a blow to the opposition parties, which had hoped to lure those ANC MPs belonging to the anti-Zuma faction into supporting the no-confidence motion.

This would have required the speaker to give permission for a secret ballot, as had been requested by the leaders of the opposition parties when they announced their plans for tabling the motion.

The National Assembly's multi-party programme committee is scheduled to meet this morning to discuss the motion.

The ANC will use that meeting to rubber-stamp the decision of its caucus.

Motshekga said the opposition parties that tabled the motion did not have valid reasons for doing so.

"If the people of South Africa, the majority of whom overwhelmingly mandate this president and the ANC to lead this country, were to learn that this august institution has entertained a motion of no confidence in the president on the basis of such frivolous allegations, their trust in the ANC and parliament would have been violated," he said.

He advised opposition parties to use the 2014 general election to elect a president of their choice instead of attempting to use parliament to change the leadership of the country.

DA chief whip Watty Watson said he had written to Speaker Max Sisulu, reminding him that attempts by the ANC to use its majority to block the tabling of the motion were a violation of the constitution.

DA parliamentary leader Lindiwe Mazibuko said it was "unprecedented and unconstitutional" for the ANC to veto debate by parliament on the president's performance.

She said this proved that the ANC was not sure it could secure the support of all its MPs if the motion were put to a vote by secret ballot.

"It is clear that the ANC is running scared today. The real reason that the party does not want the vote to take place is that its leaders cannot secure the support they need within their own ranks to vote the motion down," Mazibuko said.