Why is Chavez concerned about the growing power of the federal government?

It will affect his oil business is the right answer.

Explanation:

The South American country Venezuela follows the Federal Republic government system. Though the country is apparently pretended to be a federal republic, it is very swiftly shifting a tyrannical despotism under "Hugo Chavez the President of Venezuela. His main concerned about the increasing influence of the federal government was that it will affect his oil business. Therefore, he "nationalized" all international business ventures.

Chavez was concerned about the growing power of the Federal Government because he was afraid that it would've effected his oil business.