(CNN) – In a move that could affect the prospects for the immigration reform bill, Sen. Ted Cruz, R-Texas, announced Monday via Twitter that he plans to file an amendment to the legislation that would allow states to require proof of citizenship before registering to vote.
His announcement came in response to the Supreme Court's decision Monday to strike down an Arizona provision in its voter registration law that required identification confirming citizenship.
If the senator's amendment goes to the floor, it could throw a wrench in the already-complicated immigration reform bill. A bipartisan group of senators have been pushing the bill
The 7-2 majority said the state's voter-approved Proposition 200 interfered with federal law designed to make voter registration easier.
The state called it a "sensible precaution" to prevent voter fraud. Civil rights group countered it adds an unconstitutional and burdensome layer of paperwork for tens of thousands of citizens.
– CNN's Ashley Killough contributed to this report.