How to make this leetcode method more efficient, without using count variable or perhaps another way?

This is for leetcode problem: https://leetcode.com/problems/majority-element

There is something wrong with the way I create solutions, and not sure how to stop doing it. Basically the problem is I always create a count variable. Here is it called greatest_count. For the if statement, I create a conditional, which I think is fine, but I feel like I don't need the additional greatest_count variable here but not sure a better way to write it. I always seem to think I need to count it and check it against the previous counts. Do I need this? How can I write this without needing the count variable? or without using the greatest unique? Any ways to optimize this would be great to know.

Problem area:

if unique_count > greatest_count:
   greatest_count = unique_count
   greatest_unique = i

Here is the full code:

class Solution:
    def majorityElement(self, nums):
        unique_nums = set(nums)
        greatest_unique = 0
        greatest_count = 0
        
        for i in unique_nums:
            unique_count = nums.count(i)
            if unique_count > greatest_count:
                greatest_count = unique_count
                greatest_unique = i
        return greatest_unique

Thank you