Are the checks and balances between the branches sufficient to preserve the balance of power?

checks and balances are important, but it's not sufficient.

Explanation:

Checks and balances allowed each branches of the government to limit each other's power. But there's nothing really stopping the officials from each branches of government to work in cahoots with one another behind the scene to fool the public.

In order to preserve the balance of powers, the voters need to be involved in the process.

They need to watch over the actions that made by each branch and ensure that none of the branch installed their insiders to hold the position in other branch of the government.

do you have a list of sources to choose from?