

He also didn’t use the levers of power he had effectively. He was playing gentleman’s rules whilst the real threat to the country (from within) waited for him to get out of the way.
The Supreme Court nominations is the obvious one, but he should have been reinforcing all the checks and balances in the system, possibly even relinquishing powers away from the Office of the President where they have accumulated over 250 years.
Bin Laden wasn’t the threat. His own position was.

…because allegations don’t get it done.
We need him bang-to-rights. No wiggle room. Conclusive evidence. He’s the most powerful man in the world and he shrugs off allegations.