DA leader Helen Zille promised on Wednesday to push the corruption case against ANC president Jacob Zuma with "everything we've got".

"The principle of equality before the law is at stake," Zille told a gathering of her supporters in the town of Kirkwood outside of Port Elizabeth.

"We will drive the case with everything we have got."

Zille filed an urgent application in the High Court in Pretoria on Tuesday requesting a review of the National Prosecuting Authority's (NPA) decision to drop charges against Zuma.

She said the reasons given by the NPA for dropping the charges were irrational.

"The reasons given by Mokotedi Mpshe (NPA head) for dropping the charges against Mr Zuma were irrational and had nothing to do with the substance of the case," Zille said.

Zille received a rousing welcome to the event with the mainly Afrikaans speaking delegates singing "Dis Zille wat die wind laat waai" (It?s Zille who brings the winds).

Earlier Democratic Alliance member Donald Lee praised Zille for bringing "Winds of Change" to South Africa.

Zille told the audience that Mpshe had buckled to political pressure from the African National Congress to drop corruption charges against Zuma.

"Mr Mpshe could not be conceived to be taking a neutral decision. He expects Mr Zuma to become president. He knows exactly what happened to his predecessor Vusi Pikoli," she said in reference to the former NPA leader, Pikoli, who was fired from his job by President Kgalema Motlanthe.

"Mr Mpshe knows that if he does not behave like an ANC cadre he will have no work."

Zille, who spoke in Afrikaans, said the DA would go all-out to win the national election in 2014. First the party would try to take a number of municipalities and set an example of good governance.

"In 2014 our plan is to win the national election," she said to a shout of "Zille for President".

She accused Zuma and ANC Youth League leader Julius Malema of trying to divide the DA's supporters by visiting towns like Orania.

"They want to divide us. that is why Jacob Zuma and Julius Malema are so in love with Orania."

Malema visited Orania recently, while Zuma last week praised Afrikaners for being true South Africans.

Later Zille and her convoy chased through the Karoo to Jansenville, where she sang and danced with a small group of DA supporters. She then headed for the town Graaff-Reinet to continue her Karoo campaign trail.