head of state
chief of state

For 365 days he's been learning how to be head of state.

He was also the country's head of state from 1967 to 1989.

The country was going to be without a head of state for a day.

However, the head of state may not have very much real power.

He was the head of state until his death in 1924.

She is a head of state, but the other three are not.

The King is the head of state, but he does not have all the power in the country.

This is not always the same person as the head of state.

He is a Senator for life as a former head of state.

However, that would be bad form before the head of state.