Joe Biden and Donald Trump square off for a historic US presidential debate Thursday, with the stage set for what could be an inflection point in the 2024 race as millions of voters tune in to the clash of rivals.
The showdown -- between the oldest-ever incumbent and a convicted felon -- fires the starting gun on what promises to be a bruising summer of campaigning in a deeply polarized and tense United States still convulsed over the chaos and violence that accompanied the 2020 election.
