To sit on the fence is to refuse to pick a side. Sit on the fence for months, stop sitting on the fence, cannot sit on the fence forever.
It is a criticism, since the phrase assumes a choice ought to be made. A fence-sitter is the person who does it, and the picture is of somebody with a leg in each field.
1phrasesit on the fenceTo refuse to pick a side.
“The committee will sit on the fence until somebody forces a vote.”
sit on the fence is a phrase.
Practised in Idioms