setting up a fight against former President Donald Trump.

Pence's campaign filed a declaration of candidacy with the Federal Election Commission.

Pence will launch his campaign with a video and a speech in the early nominating state of Iowa on Wednesday, three sources familiar with the situation told Reuters last week.

Pence's run pits him against front-runner Trump, whom he once loyally stood by but refused to back when the former president attempted to overturn the results of the 2020 election won by Democrat Joe Biden.

A staunch social conservative, the former governor of Indiana has increasingly distanced himself from Trump, saying his encouragement of the rioters who attacked the U.S. Capitol on Jan. 6, 2021, endangered Pence and his family, who were in the building at the time.

Pence joins a growing field of Republican candidates, which includes Trump, U.S. Senator Tim Scott and former South Carolina Governor Nikki Haley. North Dakota Governor Doug Burgum is also planning to enter the race on Wednesday, according to a person familiar with Burgum's plans.

Former New Jersey Governor Chris Christie is jumping into the race on Tuesday, bringing the total number of Republican candidates into double digits.

The number of candidates vying for the nomination concerns many Trump opponents inside the Republican Party who fear the anti-Trump vote could be split and hand the party's nomination to the former president.