The U.S. Supreme Court sided with Arizona Republicans Thursday as it ordered the partial and temporary reinstatement of an Arizona law requiring proof of U.S. citizenship to register to vote. The law was first enacted in 2022, triggering legal challenges by the Biden administration and voting rights groups. But the Supreme Court blocked Arizona from putting into effect another part of that law, which could have prohibited tens of thousands of voters who are already registered from participating in the presidential election without proving their U.S. citizenship.