* Zuma to respond by Wednesday
* ANC still split on when Zuma should go
* Hopes for economy with Zuma on way out (Adds quotes, details)
JOHANNESBURG, Feb 13 (Reuters) - South Africa's ruling party ordered Jacob Zuma on Tuesday to step down as head of state after marathon talks over the fate of a leader whose scandal-plagued years in power darkened and divided Nelson Mandela's post-apartheid 'Rainbow Nation'.
Leading members of the African National Congress now want new party leader Cyril Ramaphosa to replace Zuma as president, ANC Secretary General Ace Magashule told a news conference.
But the party's national executive was split on precisely when Zuma should go, Magashule added, leaving the president's immediate fate still hanging in the balance.
There was no word from Zuma or his spokesman but Magashule said the president had promised to respond to the order by Wednesday. The rand weakened, with traders blaming uncertainty caused by the lack of a clear timetable.
Magashule said he had met Zuma personally to pass on the decision. "We haven't given him any deadline to respond," he said. "The organization expects him to go."
Zuma had asked the party to give him a notice period of three to six months but that had been rejected, Magashule said. "Timelines? No. The NEC believes that this is an urgent matter so it should be treated with urgency," he said.
Zuma has been living on borrowed time since Ramaphosa, a union leader and lawyer once tipped as Mandela's pick to take over the reins, was elected as head of the 106-year-old ANC in December.
Ramaphosa narrowly defeated Zuma's ex-wife and preferred successor, Nkosazana Dlamini-Zuma, in the leadership vote, forcing him to tread carefully in handling Zuma for fear of deepening rifts in the party a year ahead of an election.
Despite the damning decision to order Zuma's "recall" - party speak for 'removal from office' - domestic media said the 75-year-old might yet defy the party's wishes, forcing it into the indignity of having to unseat him in parliament.
South Africa's economy has stagnated during Zuma's nine-year tenure, with banks and mining companies reluctant to invest because of policy uncertainty and rampant corruption.
But since mid-November when Ramaphosa emerged as a real ANC leadership prospect, economic confidence has started to pick up. The rand - a telling barometer of Zuma's fortunes - has gained more than 15 percent against the dollar over that period.
Since becoming president in 2009, Zuma has been dogged by scandal. He is fighting the reinstatement of 783 counts of corruption over a 30 billion-rand (now $2.5 billion) government arms deal arranged in the late 1990s when he was deputy president.
Some within the ANC and the opposition say the Gupta family, friends of Zuma, have used their links with the president to win state contracts and influence cabinet appointments. The Guptas and Zuma have denied any wrongdoing. (Additional reporting by Olivia Kumwenda-Mtambo; Writing by Ed Cropley and James Macharia; Editing by Andrew Heavens)