A320 First Officer reported a fumes event during pre-flight due to either aircraft fuel issue or ramp fueler issue. After extended delay with no replacement aircraft available and experiencing physiological symptoms; the flight crew declared themselves unfit to fly.

Narrative

Captain and FO (First Officer) arrived to Gate XX roughly XA20 local time; when speaking to agent we were informed of a fuel spill due to either aircraft issue or ramp fueler issue. Captain and FO proceeded down the jet bridge to assess the issue and whether or not this was simply a ground clean up problem or a mechanical issue on the airplane. When stepping onto the aircraft Captain noticed the Flight Attendants were on board and unaware of the condition outside even though the fuel odor within the airplane was overpowering. Captain and FO deplaned with the FAs onto the jet bridge; and after numerous calls with Dispatch/Operations Captain eventually came to the conclusion that he was Unwilling to Operate this specific aircraft to ZZZ1 as a result of the overpowering fuel fumes within the cabin.After which the Captain; FO and FAs all exited the jet bridge back into the terminal to provide an announcement to the passengers about the delay and that the timeframe for finding a replacement aircraft was unknown. By this time the Captain and FO had spent close to an hour and half inside the aircraft and jet bridge trying to coordinate and had noticed that both of their eyes were stinging as a result of the fume exposure (initially un-noticed as a result of significant distractions trying to coordinate with Dispatch). Later in operations after filing Captains safety and odor reports both Captain and FO remarked about their stinging eyes and slight headaches. It was at this point that the Captain and FO elected to declare themselves unfit to fly for that day.