Just over a week since his disastrous debate performance, Joe Biden’s approval ratings have plummeted, and a growing chorus of his Democratic colleagues are now casting doubt over the future of the US president’s re-election bid.

Vice presidents, like Biden himself, have a strong track record of going on to become their party’s presidential nominee. Yet, Kamala Harris has struggled to find her footing as Biden’s deputy, wrestling with low approval ratings and criticisms that she has underperformed throughout her tenure.