TAIPEI, Taiwan — A delegation of former U.S. officials met with Taiwan President Tsai Ing-wen and her newly elected successor in Taipei on Monday, two days after the self-ruling democracy voted to keep their party in power in a rebuke to Beijing.

The visit by the unofficial delegation came as Taiwan, an island 100 miles off the coast of China that Beijing claims as its territory, lost one of its few remaining diplomatic relationships, with the Pacific island nation of Nauru announcing it would switch ties to China.