Joe Biden's withdrawal from the U.S. presidential race injects greater uncertainty into the world at a time when Western leaders are grappling with wars in Ukraine and Gaza, a more assertive China in Asia and the rise of the far-right in Europe.

During a five-decade career in politics, Biden developed extensive personal relationships with multiple foreign leaders that none of the potential replacements on the Democratic ticket can match. After his announcement, messages of support and gratitude for his years of service poured in from near and far.