sit on the fence
From Longman Dictionary of Contemporary Englishsit on the fencesit on the fenceto avoid saying which side of an argument you support or what your opinion is about a particular subject The weakness of the book is that it sits on the fence on important issues. → sitExamples from the Corpussit on the fence• He is the obvious choice for those who wish to sit on the fence.• You can't sit on the fence any longer - what's it going to be?• If the encyclopaedia has a weakness it is that it sits on the fence on controversial issues.