Zille, the former leader of the opposition, has been forced to apologize after tweeting that colonialism was not entirely bad.
Mmusi Maimane traveled to Zambia on Thursday to attend the trial of the country's embattled opposition leader, but says he was "assaulted" and turned back upon arrival.
Helen Zille tweeted that colonialism wasn't entirely bad and suggested she saw it as bringing some benefits.
The president fired his popular finance minister to widespread criticism.
Zuma has survived three motions since the start of 2015.
The Treasury had described the charges as being politically motivated.
The country's finance minister has been summoned by police but says he won't go.
The EFF leader said his party would not enter coalitions with either the ANC or the DA.
The ANC is in danger of losing the dominance it has held since the end of apartheid.
The Democratic Alliance used a clip of Mandela's voice in a campaign advert.
Could the opposition leader realize South Africa's non-racial dream?
The National Assembly will vote on whether to remove Zuma from office on Tuesday.
The country's highest court has ruled that Zuma violated the constitution over the Nkandla scandal.
Mmusi Maimane says that ANC members must vote to impeach Zuma over the Nkandla scandal.
The South African president used state funds to make build himself a swimming pool and amphitheatre.
The South African opposition leader says the country is being "polarized" along racial lines.
Every existing and new member of Maimane's party will have to sign an anti-racism pledge.
Newly elected opposition leader Mmusi Maimane says president must be held accountable for €19m home extension scandal