A powerful South African union federation that had been a key ally of President Jacob Zuma has become the latest group to join the rising calls for him to resign.
"There has never been so much pressure on him to go, from allies and opponents," NPR's Ofeibea Quist-Arcton reports, adding that Zuma's problems began with the widespread perception that he was mired in corruption scandals.
The reversal by the Congress of South African Trade Unions is the latest in a series of dramatic political events in South Africa. Just last week, Zuma sacked a respected finance minister and reshuffled the country's Cabinet.
As a result of the upheaval, credit ratings agency Standard & Poor's downgraded South Africa's economy to junk status on Monday — only adding to the pressure on Zuma, who has shown no sign that he will go.
The trade union federation is angry that it wasn't consulted about the Cabinet reshuffle, which Zuma has defended as a way to bring in "young ministers."
"COSATU no longer believes that the president is the right person to unite and lead the movement, the Alliance and the country," it said in a statement. "We think that after all his undeniable contribution to both the movement and government, the time has arrived for him to step down and allow the country to be led forward by a new collective at a government level."
Zuma is head of the African National Congress. The political party that led post-apartheid South Africa to freedom has governed in alliance with COSATU and the South African Communist Party, which has also recently called for his resignation.
COSATU was instrumental in Zuma's rise to power in 2009, writes South Africa's Mail & Guardian newspaper. But it has "since soured with Cosatu publicly expressing support for deputy president, Cyril Ramaphosa."
Last weekend, Ramaphosa appeared to be distancing himself from Zuma in a speech calling for national renewal, though he did not mention the president by name.
"Let us act together in unity! Unite our movement, unite our country around one goal," Ramaphosa said, as quoted by the BBC. "The goal of making South Africa a South Africa we can all be proud of — and getting rid of greedy people, corrupt people within our land."
From Durban, Peter Granitz reports for NPR that Zuma's sacking of well-respected Finance Minister Pravin Gordhan was particularly controversial: "He was replaced by a Zuma loyalist [Malusi Gigaba] with no experience at the National Treasury."
Ramaphosa also publicly criticized the dismissal of Gordhan last week.
Six opposition parties issued a joint call for Zuma's resignation on Monday, the Mail & Guardian reports. The parties said they are "united in their call for Zuma to go and our belief in the supremacy of the Constitution. The choice South Africans must make is: Zuma or South Africa. The two cannot co-exist."
There are mounting calls on social media for protests against Zuma later this week. In a tweet, the South African government described such protests as illegal.
Even several members of Zuma's own party, the ANC, have called for his resignation.
As Ofeibea reports, "all eyes are now on the ANC's National Working Committee, the high-level body that is currently meeting to try to sort out the crisis and whether it thinks Zuma should continue at the helm or not."
Some parliamentarians are pushing for a no-confidence vote and possible impeachment, Ofeibea adds, which would require dozens of ANC members to publicly defect from Zuma in order to pass.
As Ofeibea notes, "The 74-year-old president has managed to bounce back time and time again, but is certainly on the ropes."