A.N.C asks Zuma to resign.

Top leaders of South Africa’s governing party ordered President Jacob Zuma to step down on Tuesday, saying that his continued presence was eroding the “new hope” felt since the election of new party leaders in December.

In a meeting with party leaders Monday night, Mr. Zuma was defiant, insisting that he had done nothing wrong and refusing to resign, according to the local news media.

The extraordinary confrontation between Mr. Zuma and the African National Congress, the party that had backed him throughout a scandal-plagued presidency until recently, heightened a power struggle that has paralyzed South Africa, which has the continent’s most powerful economy, in the past week.

Ace Magashule, the A.N.C. secretary general, said that the party had not given Mr. Zuma a deadline to respond.

“Let’s leave it to President Jacob Zuma,” Mr. Magashule said at a news conference at party headquarters in Johannesburg. He said that the president had pleaded to keep serving for an additional three to six months before stepping down.

The drawn-out negotiations over Mr. Zuma’s future have cast a pall over the optimism that followed Cyril Ramaphosa’s election in December as leader of the A.N.C. Although Mr. Ramaphosa, deputy president since 2014, has a mixed record in both politics and business, he has spoken forcefully against corruption and is allied with A.N.C. officials with reputations as reformers.

The A.N.C.’s decision to recall Mr. Zuma culminated a week of high-level party meetings and direct talks that failed to resolve the impasse between Mr. Zuma and Mr. Ramaphosa. Seeking to avoid a confrontation that could deepen a party split, Mr. Ramaphosa had pressed Mr. Zuma to resign voluntarily.

Mr. Ramaphosa’s allies have argued that Mr. Zuma should step down as soon as possible to give Mr. Ramaphosa, as his successor, enough time to rebuild the party ahead of national elections in 2019.

Under the Constitution, Parliament selects the president, effectively putting the decision in the hands of the A.N.C.’s top leaders. Parliament can also remove him through a vote of no confidence, an option that A.N.C. leaders want to avoid, as it could deepen party divisions and keep public attention focused on Mr. Zuma, rather than on the party’s new leadership.

Opposition parties are demanding that a vote of no confidence against Mr. Zuma, scheduled for Feb. 22, be moved up to this week, putting the governing party in an awkward position. A.N.C. lawmakers would have to work with the opposition, which could then claim credit for removing the president. Or they could choose to vote against the opposition-led motion and put forward their own, prolonging the crisis.

The A.N.C.’s decision came hours after a marathon meeting of its top leaders in the national executive committee at a hotel in Pretoria, the capital. The meeting started Monday afternoon and lasted into Tuesday’s predawn hours, as the party’s leaders tried to agree on a way to handle Mr. Zuma.

Around midnight, Mr. Ramaphosa’s motorcade was seen making its way to Mr. Zuma’s residence, where Mr. Ramaphosa directly asked for the president’s resignation, according to the local news media. After the president is said to have refused, Mr. Ramaphosa’s motorcade returned to the hotel where, in a tense meeting over the next few hours, Mr. Ramaphosa pushed members of the executive committee to formally demand that the president step down.

The developments amounted to a setback for Mr. Ramaphosa, who had confidently told South Africans, who are increasingly weary of the continuing power struggle, that Mr. Zuma’s future would be finalized during Monday’s executive committee meeting. Mr. Ramaphosa had hoped to obtain Mr. Zuma’s resignation to avoid issuing an order that could deepen the fissures inside the A.N.C.

At an A.N.C. conference in December, Mr. Ramaphosa was elected to lead the party. But his margin of victory over Mr. Zuma’s chosen successor was slim, indicating the deep party split and presaging the difficulties he would face in pressing Mr. Zuma to step down as the nation’s leader before his term expires in mid-2019.