Another councillor has resigned from the DUP over its decision to share power with Sinn Fein.
The DUP's move to share power with Sinn Fein has caused resignations
Banbridge Councillor Stephen Herron said he was saddened at having to make the decision, but that he could not support the power-sharing deal.
A total of seven councillors have now left the party for the same reason - five in Ballymena, one in Ballymoney and Mr Herron in Banbridge.
The party's MEP, Jim Allister, has also quit over the deal.
A number of DUP assembly members have spoken of their concerns about power-sharing with Sinn Fein on 8 May, but none have resigned.
On Monday night, Ballymena mayor James Alexander and Councillor Robin Stirling announced their decisions to leave during a meeting of the council.
They will stay on the council as independents.
The resignations meant that the DUP lost overall control of Ballymena council.
Last year, Mr Stirling proposed a motion granting party leader Ian Paisley the freedom of the town.
However, he said he now felt betrayed by the DUP leader.