By your comment "Do you vote Republican?", I'm assuming you are in the US. Then the answer is likely yes.

Federally, the US EEOC has a page listing the "Prohibited Employment Policies/Practices" (https://www.eeoc.gov/prohibited-employment-policiespractices). It makes no references to political orientation or social causes.

Also its not covered under the "Civil Rights Act of 1964" as well.

Certain states have protection against job discrimination for public employees based on political affiliation which would cover your "Do you vote Republican?". However as you said its a consulting firm, so not applicable.

NOTE: IANAL, my SIL does HR and that was her quick answer.