A White House budget official walked into a closed session of the US House of Representatives impeachment inquiry of President Donald Trump on Saturday, where he testified about the holdup of military aid to Ukraine.

Trump impeachment hearing: In closed door session, White House budget official testifies on military aid to Ukraine

Joe Biden maintained his lead for the Democratic presidential nomination as minorities gravitated toward the former vice president and his top rival, United States Senator Bernie Sanders of Vermont, in search of the safest bets for beating President Donald Trump in 2020, according to a Reuters/Ipsos poll.

Biden and Sanders emerge as top two candidates for the 2020 US presidential elections:Polls

Democratic US Senator Kirsten Gillibrand delivered a fiery first speech as an official presidential candidate in New York City on Sunday, calling US President Donald Trump a "coward" at the doorstep of one of his most famous properties.

Democrat Gillibrand delivers 2020 White House launch speech outside New York Trump hotel

Beto O’Rourke, the youthful Texan who gained a national following with his long-shot election battle against US Senator Ted Cruz last year, on Thursday launched a bid for the 2020 Democratic presidential nomination.

Democrat Beto O'Rourke jumps into 2020 US presidential race

First-term Democratic Senator Kamala Harris of California, a rising party star and outspoken critic of President Donald Trump's immigration policies, launched her 2020 campaign for the White House on Monday in an appearance on ABC's "Good Morning America.

Indian-American Democrat Kamala Harris enters 2020 US presidential elections

Tulsi Gabbard, the first Hindu lawmaker in the US Congress, is considering to run for American presidency in 2020, according to sources close to her. On Friday, at a Medtronic conference in Los Angeles, an eminent Indian-American Dr Sampat Shivangi introduced Gabbard, 37, and said that she could be the next president of the US in 2020.

Indian-American Tulsi Gabbard may run for US presidency in 2020: Sources

Rumours of Winfrey contesting elections made headlines earlier this year

Oprah Winfrey has pearls of wisdom for 2020 US presidential candidates