Johannesburg - IEC chairperson Pansy Tlakula has failed to respond to some opposition parties' call for her to resign, UDM leader Bantu Holomisa said on Tuesday.
"She has not responded," he said.
"We are in consultation with lawyers as we speak in line with the multi-party resolution."
Opposition parties had given Tlakula until the close of business on Monday to respond to their call for her to step down.
They have threatened to take legal action if she did not.
Earlier this month, the parties said they were worried about the credibility of the 7 May elections and the parties met IEC management.
Parties calling for her resignation were the United Democratic Movement, the Azanian People’s Organisation, the African Christian Democratic Party, the United Christian Democratic Party, the Congress of the People, Agang SA and the Economic Freedom Fighters.
The Inkatha Freedom Party was originally named on the list of opposition parties but on Monday it said it was not part of the group.
Agang SA and EFF had both indicated on Monday that they were still supporting the call for Tlakula to resign.