Mike Pence, who served as Donald Trump’s vice president, is set to join the race for the White House next week.
Mr Pence is expected to launch his bid to win the nomination for the Republican Party on 7 June with a campaign video and a speech in Iowa.
The move puts Mr Pence on a collision course with his former boss Mr Trump, who is widely expected to win the nomination.
Mr Pence, 63, has served four years as Indiana’s governor. He has long been one of the Republican Party’s most vocal leaders pushing the priorities of social conservatives on issues including abortion and LGBTQ+ rights.
Mr Pence, who became Mr Trump’s running mate in 2016, has distanced himself from the former president in recent months.
The field for the GOP nomination is packed.
Chris Christie, the former New Jersey governor, is set to join the race for the White House next week, according to US reports.
The 60-year-old will confirm he is entering the battle to become the Republican presidential candidate at a gathering of supporters in New Hampshire on Tuesday, NBC reported, quoting unnamed sources.
It will be his second attempt to become the party’s nominee after he first tried in 2016.