How Zuma might leave office
Pressure is mounting on President Jacob Zuma to leave office ahead of elections next year.
Here are the ways by which he could leave office early:
Vote of no confidence
Zuma's enemies have previously sought to topple him with parliamentary votes of no confidence.
Several such motions have been tabled in parliament but failed.
During the last attempt, in August, the president's opponents fell short by only 24 votes after some lawmakers from Zuma's own African National Congress (ANC) party voted against him.
For such a motion to succeed, a simple majority of parliamentarians would be needed -- 201 in total. The ANC has 249 seats in the national assembly.
If successful, the president and cabinet would have to resign.
The speaker of parliament would become president for a maximum 30 days.
The radical opposition Economic Freedom Fighters party has tabled another motion of no confidence which is due to be debated in parliament on February 22.
The impeachment process provides three grounds by which lawmakers can strip the president of office: a serious breach of the constitution; serious misconduct; or incapacity to carry out his or her duties.
Two-thirds - 267 - of the members of the National Assembly would have to vote for the president's removal for this pathway to succeed.
If a president is removed by impeachment, he or she is replaced by the deputy president, and would lose the perks and benefits normally afforded to former heads of state.
However, the prospects for this are unclear. Parliament's oversight of the president has been criticised as being too slack.
In 2016, Zuma was found guilty of failing to uphold the constitution by the country's highest court over taxpayer-funded upgrades to his personal home.
After a court battle, Zuma agreed to pay back $500,000 (410,000 euros) that he had refused to reimburse.
In December, the Constitutional Court criticised parliament for not holding the president to account over this scandal and ordered it to draft clear rules for removing a sitting head of state.
Parliament has begun discussing such a mechanism but could take months to conclude the process.
There are two main scenarios under which Zuma could resign.
He could decide to relinquish power - likely the most dignified option.
This route would "not embarrass the president", Collette Schulz-Herzenberg, a political science lecturer at Stellenbosch University, said.
Under the other scenario, Zuma could be "recalled" by his party when its National Executive Committee meets on Wednesday and effectively forced to quit.
If he refused to step down as head of state, the party could then trigger a parliamentary confidence motion to get rid of him.
In 2008 when Jacob Zuma was head of the ANC, it recalled head of state Thabo Mbeki and shortened his term by eight months.
The party then ordered him to quit the presidency, because presidents derive their legitimacy from the largest party in parliament which elects them.
The deputy president would take power and it would be up to the national assembly to pick a new president within 30 days.
On February 6, 2018, National Assembly speaker Baleka Mbete announced that Sona has been postponed indefinitely. Sunday Times political reporter Qaanitah Hunter explains why this happened and what could happen next.