The party says it will also head to court over the removal of UDM councillor Mongameli Bobani as deputy mayor last week.
The UDM and the DA have been at loggerheads over the last couple of months.
The dispute between the coalition partners reached boiling point last week when UDM councillor Mongameli Bobani was removed as deputy mayor in a vote of no confidence.
UDM leader Bantu Holomisa now wants to challenge the motion in court.
DA councillor and Nelson Mandela Bay Mayor Athol Trollip says he is welcome to do so.
“We believe that the process was fair, in fact, the EFF, the ANC and the AIC all participated in the debate of no confidence. So there was no doubt about the quorum being in place.”
Trollip says they cannot continue with Bobani.
“So when the UDM was in our coalition we had 61 votes, that’s what we needed for the majority. But since January we have only been able to muster 59 votes because the two UDM councillors had been voting with the ANC.
“That’s the main reason why we’re removing councillor Bobani because he’s not a partner. For all intents and purposes, we have not had a coalition since January.”