IS passport copy required along with other proof of citizenship??

[sd_moving]

Hi,

While sponsoring visitor visa for parent, a person need to give proof of US citizenship.

Is copy of naturalization certificate sufficient for that or does one have to send the copy of American passport also? Passposrt hasn't come yet and papers need to be sent.

Thanks for your help.

[immihelp]

Copy of naturalization certificate is enough to prove US citizenship.