Democratic Alliance (DA) leader Helen Zille should "buy an engagement ring", Independent Democrats (ID) leader Patricia de Lille said on Sunday, as talk grew of a merger between the two parties.

"I don't know who is going to buy the engagement ring," said De Lille.

She was welcomed with cheers and whistles as she arrived on stage with Zille at the DA's federal congress in Cape Town.

"I think Helen can buy it. She can afford it," De Lille said to laughter and applause from the audience.

De Lille said that the country was a few months away from municipal elections, which would represent a "new beginning" in opposition politics in South Africa.

Crucial problems such as poverty, poor service delivery, crime and education existed that only a strong opposition could fix, she said.

"The problems are often a result of poor governance and greedy leaders. President Jacob Zuma is in the media for all the wrong reasons and in the meantime service delivery protests are on the increase.

"The real source of poverty is ANC corruption and greed."

The ANC had missed their service delivery targets for many years, but suddenly it had managed to organise the World Cup, she said.

"They remind us repeatedly that they had delivered a world-class event but for the past 16 years they had failed to deliver services."

De Lille said that she was not at all like Marthinus "Kortbroek" van Schalkwyk, who led his New National Party away from a merger with the DA to join the ANC.

"Some in the past week had tried to liken me with Kortbroek, but there is no comparison whatsoever," De Lille said.

"Unlike Kortbroek who jumped off his sinking ship into the arms of the ANC, the ID membership will all go in the same direction."

De Lille said that the difference between her and Van Schalkwyk was that he did not fight in the struggle against apartheid and nor did he fight corruption in the ANC for the next 16 years.

She said that she had travelled the country, speaking to her party members and constituents and that there was "overwhelming support" for the ID leadership to talk to opposition parties.

The ID membership had given their leadership until September to conclude negotiations with opposition parties.

"In the next few weeks the ID will work hard to find what is the best way forward for both political parties [the ID and DA]."

The more she spoke to Zille, the more she realised that the two parties had very few differences.

Zille told the congress that she and De Lille had once been determined opponents but over the past months and years they had become good friends.

"We share values and a vision and we know we have to build a new majority to be a challenge at the ballot box against the ANC," Zille said.

The outcome of the negotiations between the DA and the ID will be known in the coming weeks.

"In the next couple of weeks, who knows what will happen," Zille said.

"All I can say is 'watch this space'," Zille said.