I'm not sure, but...

Meaning

Expressing uncertainty but offering a tentative opinion.

Examples

• John: Do you think it will rain tomorrow?
• Alice: <b>I'm not sure, but...</b> I think there's a chance.
• John: Do you think we should cancel our picnic?
• Alice: Maybe. Let's check the forecast again later. <b>I'm not sure, but...</b> it might be best to.