«The Presidency in USA»

when the presidency was created, the colonies has just fought a war of independence. They didn’t want an all-powerful dictatorial figure. But they needed a strong leadership. The Article of Confederation did not provide for a single head of state. The new nation was weak and congress had no real power. There was even an idea to establish royalty. Then it was a question about the president, presidential council and a committee. So the Presidency as a single executive was established, he was chosen by Congress for a seven year term and eligible re-election.

And the removal of his appointees should be decided by Congress. The President can not remove them himself. The Congress may also refuse to appropriate money.

Albert White "The USA-history"

The Presidential Power in USA - Millar, Case, Groow.