on the fence, be

be on the fence

To be unable or unwilling to commit to a decision or a side when presented with two opposing options or possibilities. The senator has been on the fence about the issue for years. You can't be on the fence about this—you need to choose between the two, now.
See also: fence, on

on the fence, be

Also, straddle the fence. Be undecided, not committed, as in I don't know if I'll move there; I'm still on the fence, or He's straddling the fence about the merger. This picturesque expression, with its implication that one can jump to either side, at first was applied mainly to political commitments. [Early 1800s]
See also: on