The phrase "centre ground" refers to a political or ideological position that is moderate, neither leaning too far to the left nor too far to the right. It represents an area where most people agree and compromise can be reached. Full definition
The next election will also determine where the new centre ground of British politics ends up. (theguardian.com)
It will support austerity and will focus on capturing the political centre ground, though what this means will need to be considered carefully. (theconversation.com)
We haven't been organised enough and I haven't been focused enough on reaching out to that new liberal centre ground. (theguardian.com)