COLUMBIA, Mo., May 12 (UPI) -- An amendment to the Missouri constitution that would require voters to show proof of citizenship goes before the state Legislature this week.

While the aim is to protect against voter fraud, critics are concerned that large numbers of voters who can't get an ID will be disenfranchised.

"The requirements we have right now are totally inadequate," State Rep. Stanley Cox, the amendment's sponsor, told The New York Times. (NYSE:NYT) "You can present a utility bill, and that doesn't prove anything. I could sit here with my nice photocopier and create a thousand utility bills with different names on them."

The Times said the Missouri proposal is one of several proposals around the United States to beef up identification requirements. The only state to require proof of citizenship thus far is Arizona where 38,000 registration applications have been thrown out since 2004.

A concern is that immigrants and low-income Americans will be unable to come up with the required birth certificates or other documentation they will need to obtain an official state ID card.