US President Joe Biden hosts the 2023 Teacher of the Year event at the White House in Washington on April 24, 2023. (Photo: REUTERS/Kevin Lamarque)

Biden made his announcement in a video released by his new campaign team, in which he declares it is his job to defend American democracy. Biden's entry into the race follows Donald Trump's announcement in November that he would seek a second term after losing the 2020 contest to Biden.

In the two years since he took over from Trump, Biden won Congress’ approval for billions of dollars in federal funds to tackle the COVID-19 pandemic and for new infrastructure, and oversaw the lowest levels of unemployment since 1969, although a 40-year high in inflation has marred his economic record.

Biden will be joined in his 2024 quest by his running mate, Vice President Kamala Harris.