Their membership numbers might be in decline everywhere in the world, but when acting in concert, unions can still sway the balance of power within political parties.

That’s great for the unions but not necessarily for the parties nor the countries involved.

Last weekend, Jeremy Corbyn relied on the British union movement to rescue his leadership from populist pressures at the Labour Party congress. This weekend, the opposite may happen here - Cyril Ramaphosa may find his ANC presidency wrecked by Cosatu.

Corbyn wanted to contest the next general election, surely imminent, on a policy of Labour remaining neutral on Brexit while negotiating a new deal with the EU. A national referendum would then be held, with the party only then deciding what position to take on staying or going.

The grassroots activists who had put Corbyn in the leadership seat wanted an unambiguous stance, with Labour pushing “energetically” to Remain. When it came to the vote, only one of Labour’s 12 affiliated unions broke ranks and voted against Corbyn’s position.

By supporting Corbyn, the unions ensured that Labour’s fudge over Europe - Corbyn, along with maybe a third of its voters are Brexiteers - could be maintained. Labour undeniably benefited by postponing, for now, a party split on this divisive issue. But it is questionable whether the interests of the British people were served by the official opposition’s weaselling obfuscation on perhaps the biggest crisis facing the nation since World War II.

Ramaphosa, like Corbyn, finds himself poised between the rock of substantial resistance within his tripartite alliance towards his policies and the hard place of a nation in crisis. Unlike Corbyn’s comrades, Ramaphosa’s unionist allies are less likely to come to his rescue than they are to be the ones responsible for grinding him into political pulp.

It is all coming to a head, for Ramaphosa’s reformists and for South Africa. This weekend is one of the most important ANC national executive committee (NEC) meetings held since Ramaphosa took the helm and his mastery of the party will be put to a very public test. For almost two years of Ramaphosa presidency - since he narrowly snaffled the party leadership in December 2017 - the country has drifted further downwards, while CR has been distracted, supposedly busy consolidating his power base.

By the broad statistical definition, there is 38.5% unemployment, with almost 10million people unable to find work. Business confidence is at its lowest level since just before the apartheid government’s 1985 declaration of a state of emergency. Annual economic growth this year is unlikely to exceed 0.6% and Moody’s is the only major rating agency that has not yet consigned South Africa to junk bond status.

The explosive issue facing the NEC is Finance Minister Tito Mboweni’s recently proposed economic reforms to deal with what the Treasury identifies in its strategic paper as South Africa’s “unsustainable current trajectory”. Welcomed by analysts and investors, the document goes beyond the rote promise of creating jobs - one million in this case - by putting on the table substantive policy changes that are anathema to many in the ANC’s tripartite alliance.

Alliance partners Cosatu and the SACP have come out publicly in opposition. Cosatu wants the document withdrawn, since it makes the government “incoherent, confused and unreliable”.

The SACP sees in it the sinister hand of neoliberal elites like the OECD, seeking to undermine the “integrity of SA sovereignty”.

This is one showdown that Ramaphosa has to win. If he cannot triumph on this issue against the hard left, his administration will not only lose any remaining international credibility but will move closer to internal paralysis - an endless stand-off between evenly matched factions with no longer reconcilable visions of South Africa’s future economic path.

In the 2000s, former president Thabo Mbeki defied the unionists and the communists on the issue of South Africa’s economic direction. It earned him an early “recall”.

Ramaphosa’s challenge is to implement the economic changes that are desperately needed, without triggering the same response.

* Follow WSM on Twitter @TheJaundicedEye