1996 Isuzu Trooper won't start

For the past 6 months the car has had difficulty starting. I would have to depress the clutch pedal of couple of times to engage the start. I thought maybe the safety switch was going so I replaced it after the car finally wouldn't start at all. Nothing changed so I tried the battery. I put the charge/fast start on it and it started right up. It wouldn't start unless the charge was on it. I switched to a new battery, still nothing. It just clicks. Do you have any other ideas?