"The Constitution, our national compact, is above party-politics. It must stand as governments come and go, including this one [the ANC government]," Mazibuko told delegates at the party's provincial congress in Pretoria.

She said the party's strength in Parliament would ensure that it could oppose any changes the ANC wanted to make to overturn the foundational values and principles of the Constitution.

These were premised on non-racialism, the separation of powers, the independence of the judiciary, unity and equality in diversity.

"We will do whatever we must to defend and protect these values," she said.

Mazibuko admitted that the DA's target to double its vote in the next election was ambitious.

"We aim to win 30 percent of the national vote in 2014... It is an ambitious target, yes, but it is also one which we have reached through a great deal of research."

She said it was possible given that currently the party had the support of 24 percent of the population which meant that one in four South Africans was a DA voter.

One of the primary goals would be to govern Gauteng either by winning outright or in a coalition.

"If the DA wins here, we can win everywhere. If the DA can govern Gauteng in 2014, we can govern South Africa in 2019," said Mazibuko.