Former Republican vice president Mike Pence, who incurred Donald Trump's wrath by refusing to support his effort to overturn the results of the 2020 election, is set to enter the 2024 presidential race against his former boss on June 7, two sources familiar with the situation told Reuters.

Pence will launch his campaign with a video and a speech in the early nominating state of Iowa, the sources said.

A staunch social conservative who stood by Trump throughout his time in his office, Pence has increasingly distanced himself from the former Republican president since his election defeat.

Pence said that Trump's encouragement of the rioters who attacked the US Capitol on Jan 6, 2021, put him and his family in danger.

Trump has a massive polling lead in a Republican field that now has more than 10 declared candidates, a dynamic that could splinter the primary opposition against the former president.

Yesterday, Pence's polling average in the Republican field was less than four percent, compared to Trump's 53 percent, according to a RealClearPolitics average of polls.

Pence has continued to embrace many of Trump's policies, while portraying himself as an even-keeled and consensus-oriented alternative.

He has also appealed more directly to the evangelical Christian community, having spent significant time in recent months touring mega-churches across the country.

The success of his campaign will hinge on whether he can attract enough backers of Trump's policies who are turned off by the former president's rhetoric and behaviour to build a viable coalition.

Pence - a former governor of Indiana and a one-time party leader in the US House of Representatives - will also test voters' appetite for an establishment Republican in a party where voters have increasingly turned to outsiders.

- Reuters