MOSCOW (AP) — The powerful tenures of China’s Xi Jinping and Russia’s Vladimir Putin are looking as if they will extend much deeper into the 21st century than anyone originally expected. What’s more, as they consolidate political control at home, sometimes with harsh measures, the two leaders are working together more substantively than ever. That represents a growing challenge to the West and the world’s other superpower, the United States, which elects its leader every four years. This week, Putin signed a law allowing him to potentially hold onto power until 2036. Xi did something similar in 2018.