Just a personal view...
Try not to think of it in terms of "oppose" (although I recognise that the reality is often conflict) since this is a rather negative starting point. Whatever issues have given rise to your dissatisfaction, maybe try and present it as how you will strive to improve matters.
Engage the other councillors (often easier said than done) and see if you can get members of the public to speak in favour of you assuming the chair - "if" your PC facilitates public participation at the Annual meeting.
Bear in mind, the existing chair remains in the chair for the annual meeting and until the vote to continue or replace. They also have the casting vote in the case of a tie so they start with a small advantage.
Another thing to bear in mind, of course the chair has a degree of influence over the direction of travel, they are NOT a unilateral force of authority. A PC travelling a less than perfect course is not ONLY the fault of the chair but of ALL councillors too.