JOHANNESBURG — It is, in South Africa’s political parlance, the season of the two centers of power.

In December, Cyril Ramaphosa was elected leader of the African National Congress and, given the party’s pre-eminence, he immediately became the nation’s president in waiting.

That left President Jacob Zuma — the former leader of the party who had backed Mr. Ramaphosa’s rival — still in charge of the government, possibly until the next national elections in mid-2019.

And now the single question driving the politics of South Africa has become one of timing. When will Mr. Zuma cease to be South Africa’s president?

As that question hangs in the air, the people around the two men have to decide which one to back, how strongly and when. It is as if an older sun has lost its gravitational pull to a newer one — and the orbiting planets, in some confusion, have been realigning themselves.