I'm a software professional working for a start up and I have worked on many different technologies and platforms at that company. I am working for them for 1+ years and they are impressed with my performance. I got to know about about that in a meet. My total experience is 3 years(including all my part time jobs).

I have some juniors and majority of them are still learning they take too much time to complete their assigned tasks. I've helped them as much as possible. I can clearly say that deadline will be after 4 days and submission will be done after 10 days!! Like we take too much of time. My lead and me have struggled a lot but no use.

That ruined my lead he was excellent at technologies, but due to team players problem he got a bad feedback he couldn't tolerate for a long time and he left. Now the company has turned their eyes on me and they said me today noon that I'll be put on tech lead position from Monday(after 2 days).

My tech lead who was a genius, couldn't handle this. How can I? This is one of the thing that's killing me from noon.

I would like to reject this tech lead position's offer some how. I'm planning to say that I don't have enough experience. I just have only this reason to say. You guys might say like "say the actual problem" that is caused from juniors. But they already know it. They tried to convince my tech lead with that as well (Company screwed him even after knowing that). The work is too heavy and challenging as well. We work for more than 12 hours a day(Start up as you guys might know). I don't like to leave this company but I need to reject this tech lead position offer.

How can I reject? Or how to handle things if I accept it?