They said on Tuesday Zuma’s "inexplicable delays" caused uncertainty.
The DA, ACDP and IFP called on Zuma to assent to the bill after Parliament approved it last month.
IFP MP Mkhuleko Hlengwa said: “Parliament thoroughly dealt with the constitutional questions that he had raised. We want to impress upon the president to prioritise this bill.”
Steve Swart of the ACDP said the international community was waiting on Zuma to assent to the bill to meet international standards.
Analysts said Zuma's signature on the bill was an international requirement.
Dawie Roodt, chief economist at Efficient Group, said international financial institutions, investors and ratings agencies were already asking questions about the delays.
He could think of no reason for Zuma's delay other than political considerations.
The bill needed to be signed into law to meet international standards.
Neither Zuma’s spokesperson, Bongani Ngqulunga, nor Treasury spokesperson Mayihlome Tshwete could be reached for comment.