Joe Biden tonight struck a blow in the race for the White House by naming Kamala Harris as his running mate, making the California senator the first Black and South Asian American woman to run on a major political party's presidential ticket.

"I've decided that Kamala Harris is the best person to help me take this fight to Donald Trump and Mike Pence and then to lead this nation starting in January 2021," announced Biden.

The two are set to appear together for the first time for a speech on Wednesday in Wilmington, Delaware.

Harris' selection comes months after Biden committed to picking a woman to join him on the Democratic ticket. 

Harris, 55, is now the third woman to serve as a vice presidential candidate for a major political party, following Geraldine Ferraro as the Democratic vice presidential pick in 1984 and Sarah Palin as the Republican vice presidential pick in 2008.

Aware that his age could be a concern to some voters, Biden, 77, has said that he is "a bridge" to a new slate of Democratic leaders, and by selecting Harris, more than 20 years his junior, he has elevated a leading figure from a younger generation within the party.